Gletters et al: honour locale changes and reload wordlist at startup

Otherwise we use the first loaded wordlist also after having changed
the locale.
Wordsgame: minor fixes for french wordlist
core: VirtualKeyboard: add support for special keys and shift
in particular

Special keys are modifier keys like shift/alt/meta etc. that modify
the value of a normal key. They are tracked in the key-model and allow
to change the modifier bitmask on each virtualkey.

For now only "Shift" has been implemented to allow for lower and
uppercase letters on the same VirtualKey. It is off per default and
can be activated by the shiftKey property. Note, that a client can
define the shift-modified key-value as he likes using the "shiftLabel"
property in the layout map.

Special keys are put in a seperate key row at the bottom to simplify
layout rendering.
Gletters at al: use shift key on the VirtualKeyboard if necessary

For large layouts the VirtualKeyboard became unusable on small
displays.

If we have both lower- and uppercase letters we now activate the shift
key on the VirtualKeyboard.