Make debugger tooltip API more general, have the engines check the
correct file type, figure out the expression and context from the text
editor.

Put common functionality in watchutils.cpp. In the CDB engine, check
whether a tooltip expression is a known variable within the stack frame
context. If so, retrieve via symbol group or dumpers. Cache by function
and expression.
Reviewed-by: hjk <qtc-committer@nokia.com>

Modify engine creation funcs to populate a list of option pages
to be able to handle engine enabling independently of the
actual engine creation.

Introduce API to debug engines and debugger manager to do this.
Reviewed-by: hjk <qtc-commiter@nokia.com>

script debugger

Conflicts:

	src/plugins/debugger/cdbdebugeventcallback.cpp