#57 message window vs. continuation lines

[Oswald Buddenhagen]

indented output lines from gcc are continuations. the
viewer should consider this.
physically merging the lines (either into one big line or
by joining them into a single multi-line item) would make
big messages unnavigable, so any merging must be
logical only.
when the cursor enters an indented line, the "master
line" it belongs to should be searched, so the offending
source line is highlighted immediately even when
scrolling up through the message window.
additionally, some key combos (maybe ctrl-up/down)
should allow skipping to the prev/next master line.