Allows various text views to handle "tap-hold" characters (fixes #91)

Adds an internal variant of SLKeyboard's typeString method,
which can fall back on the JavaScript setValue method if
the normal type string mechanism throws an exception.

Causes Subliminal UI element classes to use the new method
when appropriate.
Merge pull request #95 from inkling/aegolden/fix_91

Allows various text views to handle "tap-hold" characters (fixes #91)