First commit of usefulFunctions feature branch

   Added *.swp vim temporary files to .gitignore
   Created <usefulFunctions.lua> which now contains only the <ls> function
   Required the library above into <init.lua>
   Updated documentation (<README.md>)
'Problems' with # sign in the documentation
Improved documentation for <ls> function
Bug fix and revert sys.execute to sys.ls

   <require> requires the additional <eex/> to point to functions within the
      eex package
   <sys.ls> deals also with nil argument, sys.execute('/usr/ls')
      avoids using colours by default, but is not necessary if sorting on Linux
      is not performed
Added test on not existing $DATASET environment varialbe
Moved functions to local eex namespace + corrected mispelled DATASETs
Update README.md

Added eex.datasetsPath documentation
Cleaning up the code

Changed comments adding the <eex.> prefix
Corrected $EEX_DATASETS spelling
Added an 
 to whatever <dataset> was missing it
Merged edits of the <README.md> done on the Github website
Merge branch 'usefulFunctions'

eex.ls - ls unix like function
eex.datasetsPath - fetchs the $EEX_DATASETS environment variable