HaikuDepot TextView: fix merging of spans

When adding two successive spans with identical styles, they should be
merged into a single span. However, all prevous spans in the view were
accidentally removed.

Change-Id: I4b2d21331ba97cf54a0db83e7638e23bd2303a63
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7128
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

HaikuDepot: Remove Custom List

Further removal of the use of custom list class;
this time part of the test engine inside HD.

Relates To #15534

Change-Id: Ia1f1d7c2577f92bba96da392fd48949a13b5a169
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3745
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

Paragraph: Added EndsWith(BString)

HaikuDepot: Clean up trailing whitespace.

HaikuDepot: Paragraph: Fixed typo in PrintToStream()

Renamed HaikuDepot's home to haikudepot.

* This closes #10699. I mentioned that to stippi after his first commit
of HaikuDepot, anyway :-)

Paragraph: Added EndsWith(BString)

HaikuDepot: Clean up trailing whitespace.

HaikuDepot: Paragraph: Fixed typo in PrintToStream()

Renamed HaikuDepot's home to haikudepot.

* This closes #10699. I mentioned that to stippi after his first commit
of HaikuDepot, anyway :-)