Some flag settings used to be stored in a keyboard layout extravalue setting. This
change:
- Introduces the capability of setting such specific flags in values/config.xml
- Retains the ability to use extravalues (for layout-specific settings), though
  there is no more any such setting at the moment.
- Fixes a bug where loading a dictionary from outside does not initialize the flags.
- Moves Flag to another class.

Note: this needs I705ec68c to avoid breaking the build

Change-Id: Ia7703aae3215b06c0b3cb792821649806e8998c1