Enable user to choose how comparison is performed

[delphidabbler]

Implement a command line option that specifies how comparison is performed.

Option could be something like -c xxx and/or --compare=xxx where xxx is one of:

• lt - check if file 1 date < file 2 date (i.e. file 1 is strictly older) - this is the current action and could be left as default.
• lte - check if file 1 date <= file 2 date (i.e.file 1 is older or same as file 2)
• eq - check if both file dates are the same
• gte - check if file 1 date >= file 2 date (i.e. file 1 is newer or same as file 2)
• gt - check if file 1 date > file 2 date (i.e. file 1 is strictly newer)

Return 1 if the conditions apply or 0 if conditions fail.

[delphidabbler]

Also added neq "operator" to list above and added numerous aliases for each operator.