* ignore .tx folder
 * cmake: when UPDATE_TRANSLATIONS=ON, extract new strings only to the
english translation file.
 * added info in CONTRIBUTING.md
 * updated english translations

Translations have been updated.

Imported unzip methods from OSDaB-Zip project;
Adds a soft dependency on zlib to oracle; if lib if not found, oracle
will continue to compile and work but without zip support.

 * Always install “release” plugins
 * install only plugins actually used

fixes #411

You won’t have to copy manually all the dlls in the release directory
anymore

Without this change, make install and make package would require “sudo”
under osx

Without this change, make install and make package would require “sudo”
under osx

* Remove cockatrice_HEADERS (obsoleted by automoc)
* Remove compilation flags definition and Qt4 finding calls
* Make use of CMAKE_INSTALL_PREFIX
* use INSTALL(TARGETS) in place of INSTALL(PROGRAM)
* Osx: create a proper application bundle
* Added comments