#173 [scim-tables] add option to disable the "shift" hotkey

[LI Daobing]

From: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=335040

The "Shift" hotkey comes from the Microsoft pinyin input methods. However, it is very frustrating because it is very easy to accidentally hit the "Shift" key (e.g., when thinking about how something should be typed) and then all the partially-typed characters are lost. Also, input methods used in Taiwan and Hong Kong traditionally do not have a "Shift" hotkey, so when the "Shift" hotkey changes the input mode to "English", the user will have a hard time figuring out why he/she cannot type Chinese any more.

For this reason, I think it is essential to have some way to completely disable the "Shift" hotkey. The "Ctrl+Space" hotkey already does the same function.