fixes #411

They are needed to fetch prices from deckbrew and possibly, in the
future, for ssl server connections

* Move all cmake-related files in a new “cmake” folder
* move nsis files in there, too, since they are templates parsed by cake
* retrieve git version once when cmake is run, and use it for both
creating version_string.h/cpp and for package naming

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

 If none of the gameboard images is set and and the user’s data
directory doesn’t contain a “zonebg” directory, create the directory,
copy contents from cockatrice’s app bundle and sets the config
accordingly.

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

 If none of the gameboard images is set and and the user’s data
directory doesn’t contain a “zonebg” directory, create the directory,
copy contents from cockatrice’s app bundle and sets the config
accordingly.

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

Additional: remove duplicate if(linux) and merge rules together

* 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

The global shortcuts were removed in favor of key events
which are only triggered when a widget has focus. This is
necessary to allow different widgets to react differently
to the 'enter' key. The current key configuration is:
search edit focused:
  * left/right: decrease/increase card count for selected database card
  * enter: add selected card to deck
  * ctrl-enter: add selected card to deck sideboard
  * ctrl-left/right: decrease/increase card count in sideboard for selected card

database focused: the same as with search edit.

deckview focused:
  * left/right: decrease/increase card count for selected deckview card
  * enter: increase count for selected deckview card
  * delete/backspace: delete selected card from deck

cardframe is now a stacked widget that prefers to show the card picture
only so that the screen can be more space efficient and the card pixel
map can be displayed as a larger size. however if the card pixel map
can not be loaded for some reason, the cardframe class will automatically
switch to the text version of the card.

a menu item was added under the database menu to allow for users to
prefer card text only.

renamed filter list modules to filter tree to more accurately reflect
the nature of the data structure.

filter builder takes filter options from user, then adds
completed filters to the filter tree. the filter tree does
not currently do anything. in the future it will filter the
cards in the database view.