Try to load custom dumpers using shared library injection
first as it is faster and does not rely on the symbol
for LoadLibrary being known to the debugger. Keep
call loading as fallback. Move the rest of the initalization
to the first dumper call, removing the need to break at main().

This is a step towards fixing Task: 243747

and find scopes (but below the main selection)

The improved traditional bar will hopefully keep everybody happy.

When the block highlighting was enabled, it would still get removed when
the mouse left the extra area. Now it changes back to the text cursor
position.

Done with mae.

The highlights would extend on top of the right column margin. It looks
better when they don't.

Done with mae.

This new look fits better with the new behaviour. Also, the
collapse/expand markers are now drawn by the style.

this avoids unnecessary QByteArray constructions