abc.sh: simplified msg1 outputs

There is no need to print the location being archived, backed-up or
copied again. msg1 just notes completion now.
abc.sh: added TODOs

* Improve tar flags to detect compression
* Separate the generic variables which can be changed from those that cannot
abc.sh: make exclusion file optional

An exclusion file for the Copy and Backup operations
is now specified with the -e option.
abc.sh: add new option for deleting old backups
and archives.

Option -D allows old backups or old archives to be removed.
These are specified with either -a or -b.
The number of months to remove is specified with -n <num>.
abc.sh: dry-run option now applied to -B and -C, as well as -D
abc.sh: edit _tarFLAGS to detect compression

Include -a option in tar flags to detect compression from tar extension
(replaces -J option)
abc.sh: hard coded date variables

Hard coded variables for naming tar achives and the directory structure
for backups. Because -D option depends on this naming to work, therefore
it should not be variable!
abc.sh: new msg output for errors

Message outputs that represent some kind of error now have their own
msg function (red and bold!)
abc.sh: add -V option, to show version number
abc.sh: changed date command to work on FreeBSD
abc.sh: fix path error in delete_older_than function
version bump 0.1.1 > 0.1.2
abc.sh: attempt to make variable quoting correct and consistent
abc.sh: simplified aritmetic variables

Tests can be done on a variable e.g. (( _TESTVAR )) without needing to
use "$" to access the value of the variable, e.g. (( ${_TESTVAR} == 1 ))
version bump 0.1.2 > 0.1.3
edit .gitignore
Revert "abc.sh: edit _tarFLAGS to detect compression"

The -a option does not work on FreeBSD.

This reverts commit b79b5025495a1b0c2259ac7888ac96b922aab3da.
version bump 0.1.3 > 0.1.4