aix works now so far, but -R doesnt work - now it does but decryption fails for some unknown reason.

libpcp/z85.c:148 free(z85) leads to coredump on aix sometimes

add more abstract en+de-cryption() functions to libpcp/crypto, which
work with already en+de-coded in+out-put.

Bug: pcp_z85_decode() segfaults at z85.c:83 if input consists of "-----" only.

Bug: pcp_z85_decode() fails if after end marker follows something, even whitespaces

key++: normalize id and lc()