Input mode switch and indicator

Experimental input mode switch. Allow users to type both Chinese and English. User can switch between Chinese input mode and English (a.k.a. Direct input / 英數) just by toggling / pressing SHIFT.

Fix #87 (closed)

Fix #59 (closed)

User Experience Design

Based mostly on older version of Windows system:

• In Chinese input mode (implicit) by default.
• Can switch to-and-from English input mode (英數), a.k.a. pass through mode, by either the top menu toggle or SHIFT button.
• The SHIFT button hot key is only triggered if only the SHIFT key is pressed an released. Prevent messing behaviour of other SHIFT+ situation.
• When toggled to English input mode, input engine stop processing any of the input and pass through to normal keyboard handling.
• Half-width / Full-width character mode only has effect in Chinese input mode.
• Top symbol signify both the input mode and the Half-width / Full-width character mode.

User Interface

Input Method	English Input Mode	Chinese Input Mode (Half-width chars)	Chinese Input Mode (Full-width chars)
倉頡 Cangjie
速成 Quick

(UI pending translation)