Splits longish v8js.cc file into pieces. It used to contain the
definitions of all V8Js exception classes, the V8Js class itself as
well as the V8Object/V8Function classes... besides the module setup
code itself.
This change factors out all exception class definitions into a
seperate pair of files (v8js_exceptions.*).
The V8Js class definition itself is moved to v8js_class.* pair,
with the v8 init & call code moved to v8js_v8.* pair
and the watchdog timer to v8js_timer.* pair.
The V8Object/V8Function code was moved to v8js_v8object_class.*
pair, not differentiating between the two like before.
