Updated pl.dir.file_op to return true on success and false on failure when falling back to DOS commands.

The fallback to DOS commands (when alien is not available) now returns false,err on failure and true on success as stated in the documents.
Tests for copying have been added and move has been updated.
Fixed utils.execute returning different results with Lua 5.1 and Lua 5.2
Added test for the change
workaround for issues with pl.lapp with amalg.lua
problem with tablex.count_map with custom comparison
Improved detection of unsupported short flags

Parsing of an unsupported short flag was failing with:

    attempt to index local 'flag' (a nil value)

Example usage: myscript.lua -ab
Where -a is the unsupported flag.
Merge pull request #111 from fidlej/patch-1

Improved detection of unsupported short flags - thanks, man!
Merge pull request #102 from chrisjaquet/Updated-return-values-for-pl.dir

Updated pl.dir.file_op to return true on success and false on failure...
Merge pull request #105 from mpeterv/fix_utils_execute

Fixed utils.execute returning different values for Lua 5.1 and Lua 5.2