Make helpex to be able to work with more xhp files at one time
 - Add new input flag "-mi" which means multiinput
 - Input is a file include pathes to xhp files
   (these are in the same directory so their strings
   are in the same po file)
 - Output is a file include pathes to dest xhp files
 - Merge reads all po entry from the specified po file
   if MergeDataFile ctor's second parameter is empty

Rewrite makefiles to work with new syntax
Plus Delete some unused code

Change-Id: I5eb12d7a6f5e9cda378788410d3c50052eb752b8