Regenerate language-specific user dict list when language of underlying text
changes. Not just when the user overrides it from the top menu.

Not a count of code-units, nor a count of code-points, but try and follow
http://unicode.org/reports/tr29/ and present the grapheme count.

Add a few representative tests to try and avoid gotchas.

It uses a hardcoded plain "strip" command anyway, which hardly will
work for foreign executable file formats.

The sole reason for that late class was the overloaded
Range::expand() method - but it's actually quite easy to
disambiguate that for boost::bind.

Added a local class for it: there may be a better fix, but it avoids the
build to break.

Removed a few remaining includes

Semantically, B2IBox represents a pixel rect much better than
B2IRange - replaced all occurences in and around the software
renderer, and client code.

Added docs to the range/* classes, removed methods the compiler can
generate for us, removed unused header, and cleaned up visibility
markup (inlines don't really need to be exported).

Made the distinction more clear, added appropriate tests to nail
behaviour.

Moved the implementation detail that SalFrames lifetime is handled
manually in vcl out of basebmp & into vcl. Added lightweight wrapper
class to decouple damagetracker lifetime from GtkFrame lifetime.

This reverts commit 69e4dd12.

The SolarMutex is integrated with native gtk+ toolkit locking so
this is semantically equivalent and rather less problematic.

Improvements include:
- don't create widgets when calculating the native region size, but use
  GtkStyleContext instead
- refactor the native control drawing cycle
- theme scrollbars
- theme menu radios/checks/separators/arrows

This also finishes the uncoupling of NSS from the --with-system-mozilla.