add support for template output mode with new option --templage <tmpl> (#47)

tablizer.pod

@@ -33,6 +33,7 @@ tablizer - Manipulate tabular output of other programs
       -J, --jsonout                      Enable JSON output
       -C, --csv                          Enable CSV output
       -A, --ascii                        Default output mode, ascii tabular
+      -P, --template <tpl>               Enable template mode with template <tpl>
       -L, --hightlight-lines             Use alternating background colors for tables
       -o, --ofs <char>                   Output field separator, used by -A and -C. 
       -y, --yank-columns                 Yank specified columns (separated by ,) to clipboard,
@@ -80,16 +81,16 @@ may also  use the  B<-v> option  to exclude all  rows which  match the
 pattern. Hence:
 
    # read from STDIN
-   kubectl get pods | tablizer
+   > kubectl get pods | tablizer
 
    # read a file
-   tablizer -r filename
+   > tablizer -r filename
 
    # search for pattern in a file (works like grep)
-   tablizer regex -r filename
+   > tablizer regex -r filename
 
    # search for pattern in STDIN
-   kubectl get pods | tablizer regex
+   > kubectl get pods | tablizer regex
 
 The output looks like the original  one. You can add the option B<-n>,
 then every header field will have a numer associated with it, e.g.:
@@ -99,7 +100,7 @@ then every header field will have a numer associated with it, e.g.:
 These numbers denote the column and  you can use them to specify which
 columns you want to have in your output (see L<COLUMNS>:
 
-   kubectl get pods | tablizer -c1,3
+   > kubectl get pods | tablizer -c1,3
 
 You can specify the numbers in any order but output will always follow
 the original order.
@@ -107,11 +108,11 @@ the original order.
 However, you may also just use the header names instead of numbers,
 eg:
 
-   kubectl get pods | tablizer -cname,status
+   > kubectl get pods | tablizer -cname,status
 
 You can also use regular expressions with B<-c>, eg:
 
-   kubectl get pods | tablizer -c '[ae]'  
+   > kubectl get pods | tablizer -c '[ae]'  
 
 By  default tablizer  shows  a  header containing  the  names of  each
 column.  This can  be disabled using the B<-H> option.   Be aware that
@@ -236,7 +237,7 @@ and append the flag. The following flags are supported:
 
 Example for a case insensitive search:
 
-    kubectl get pods -A | tablizer "/account/i"
+    > kubectl get pods -A | tablizer "/account/i"
 
 If you use the C<!> flag, then the regex match will be negated, that
 is, if a line in the input matches the given regex, but C<!> is
@@ -307,7 +308,7 @@ Lets take this table:
 
 We want to see only the CMD column and use a regex for this:
 
-    ps | tablizer -s '\s+' -c C
+    > ps | tablizer -s '\s+' -c C
     CMD(4)
     bash
     ps
@@ -340,7 +341,7 @@ use a regexp containing the C</> character, eg:
 
 Example:
     
-    cat t/testtable2
+    > cat t/testtable2
     NAME  DURATION
     x     10
     a     100
@@ -348,7 +349,7 @@ Example:
     u     4
     k     6
     
-    cat t/testtable2 | tablizer -T2 -R '/^\d/4/' -n
+    > cat t/testtable2 | tablizer -T2 -R '/^\d/4/' -n
     NAME    DURATION 
     x       40      
     a       400     
@@ -365,7 +366,7 @@ useful which enables I<extended mode>. In  this mode, each row will be
 printed vertically,  header left,  value right,  aligned by  the field
 widths. Here's an example:
 
-    kubectl get pods | ./tablizer -o extended
+    > kubectl get pods | ./tablizer -o extended
         NAME: repldepl-7bcd8d5b64-7zq4l  
        READY: 1/1    
       STATUS: Running  
@@ -379,7 +380,7 @@ The option B<-o shell>  can be used if the output  has to be processed
 by the shell,  it prints variable assignments for each  cell, one line
 per row:
 
-    kubectl get pods | ./tablizer -o extended ./tablizer -o shell
+    > kubectl get pods | ./tablizer -o extended ./tablizer -o shell
     NAME="repldepl-7bcd8d5b64-7zq4l" READY="1/1" STATUS="Running" RESTARTS="9 (47m ago)" AGE="4d23h" 
     NAME="repldepl-7bcd8d5b64-m48n8" READY="1/1" STATUS="Running" RESTARTS="9 (47m ago)" AGE="4d23h" 
     NAME="repldepl-7bcd8d5b64-q2bf4" READY="1/1" STATUS="Running" RESTARTS="9 (47m ago)" AGE="4d23h" 
@@ -389,9 +390,22 @@ You can use this in an eval loop.
 Beside normal  ascii mode  (the default) and  extended mode  there are
 more output modes available: B<orgtbl>  which prints an Emacs org-mode
 table and  B<markdown> which prints  a Markdown table,  B<yaml>, which
-prints  yaml encoding  and CSV  mode, which  prints a  comma separated
+prints  yaml encoding  and B<CSV>  mode, which  prints a  comma separated
 value file.
 
+A special output mode ist the B<Template> mode, activated with the
+option C<--template>. Template language is the Golang template
+language: L<https://pkg.go.dev/text/template>. You can also use lot's
+of additional functions from:
+L<https://masterminds.github.io/sprig/>. Here's an example:
+
+    > kubectl get pods | tablizer --template "{{.name}} is {{.status}}"
+    alertmanager-kube-prometheus-alertmanager-0 is Running
+    grafana-fcc54cbc9-bk7s8 is Running
+
+
+You can use header names as variables.
+
 =head2 PUT FIELDS TO CLIPBOARD
 
 You can let tablizer put fields to the clipboard using the option