Improve the logging so all messages going to stderr are also
captured and stored into the generated log files.  Change the
custom messaging functions in lib/functions.sh to output the
messages to stdout instead of stderr, because there was no
real need or benefit from using stderr.

Complete the "no colored output by default" changes started in
the previous commit, by extending the color output settings to
"pacman" and "makepkg" themselves.

At the same time, perform some improvements and code cleanups,
as spotted while going through the source code.

Signed-off-by: Dragan Simic <dsimic@manjaro.org>