Port mate-dictionary to Gsettings

This ports mate-dictionary from MateConf to Gsettings (and a flat file to store window state). The applet is also ported to use the same gsettings as the main program, but it still needs MateComponent usage removed (I could only test the applet on MATE 1.4). I'll work on the matecomponent removal next.

Based on:
http://git.gnome.org/browse/gnome-dictionary/commit/?id=ddb5e0ba3412e4fd1b643faa75fa86294d89730e

http://git.gnome.org/browse/gnome-dictionary/commit/?id=973e822499d0f3ef10356fbd9f28b93afea9e01d

http://git.gnome.org/browse/gnome-dictionary/commit/?id=cd5eb12bd5e8795596b0d6c2cdc8398fca8eef08

http://git.gnome.org/browse/gnome-dictionary/commit/?id=dbc62a91ef516646f9080cd26ab69d2f469d2a67

http://git.gnome.org/browse/gnome-dictionary/commit/?id=4e6002b6eb13ada093bb9ebc63f5a1fd1535dc71