pkg-config uses uppercase for its _CFLAGS and _LIBS variable names.
So we follow suit and convert all _cflags and _libs variables to
uppercase for more consistency.

New syntax @[addr]:port introduced to enable that. Root problem was IPv6
addresses contain colons.
Also somewhat enhanced debugging messages.

This is done by specifying $ActionMailTo multiple times. Note that this introduces a
small incompatibility to previous config file syntax: the recipient
list is now reset for each action (we honestly believe that will
not cause any problem - apologies if it does).

reduced dependencies, moved non-runtime files to its own directory except
for some whom's status is unclear