HaikuDepot TextView: add a way to relayout when document changed

When adding new paragraphs or otherwise editing a document from outside
the view, the layout needs to be recomputed and the view invalidated.
Otherwise, the changed text is not shown.

Change-Id: Id3c60d8b510443f71ebbc805b7b7ca5b35220fd5
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7131
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

HaikuDepot TextView: add support for hyperlinks/clikable areas

Specific text spans can be assigned a cursor and BMessage to send when
they are clicked. This allows for implementing hyperlinks, specific
popup menus, and clickable text of any type.

With some extra work it can also be used to implement spell checking
suggestions, buttons, and so on.

Change-Id: I390e0c44656da76a950c432bdd934bd51af49baf
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7130
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

use .IsSet() instead if .Get() != NULL

Change-Id: Ia2b7a719fd398e78cc3b11d4f7b02cb81179f65f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3488
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

apps: Convert to using Set*UIColor.

Signed-off-by: Augustin Cavalier <waddlesplash@gmail.com>
Patches 0045-0075, 0077-0087 from looncraz, unmodified.

HaikuDepot: Text: Fix regression for B_SELECT_ALL

An Invalidate() was removed, since I originally planned to remove the need
to invalidate on selection changes, but then saved it for later.

TextDocumentView: Fixed leak of BMessageRunner.

HaikuDepot, text framework: Rework blinking the caret

Make sure that the caret starts blinking half a second after it last moved.
The previous solution using Pulse() had a number of problems:
* The caret could be hidden during moving it or during typing. It would then
be shown again very soon after, i.e. when typing the next character or
when moving it to the next offset. But it looks bad anyway.
* When the caret stopped moving, it started blinking a random amount of
time afterwards, getting back into the rhythm of Pulse() messages.
However, starting to blink a constant time after the caret last moved,
looks much more satisfying.

HaikuDepot: Clean up trailing whitespace.

HaikuDepot: Added SetSelectable(bool) to TextDocumentView.

HaikuDepot: React to B_SELECT_ALL in custom text view

Renamed HaikuDepot's home to haikudepot.

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

HaikuDepot: Text: Fix regression for B_SELECT_ALL

An Invalidate() was removed, since I originally planned to remove the need
to invalidate on selection changes, but then saved it for later.

TextDocumentView: Fixed leak of BMessageRunner.

HaikuDepot, text framework: Rework blinking the caret

Make sure that the caret starts blinking half a second after it last moved.
The previous solution using Pulse() had a number of problems:
* The caret could be hidden during moving it or during typing. It would then
be shown again very soon after, i.e. when typing the next character or
when moving it to the next offset. But it looks bad anyway.
* When the caret stopped moving, it started blinking a random amount of
time afterwards, getting back into the rhythm of Pulse() messages.
However, starting to blink a constant time after the caret last moved,
looks much more satisfying.

HaikuDepot: Clean up trailing whitespace.

HaikuDepot: Added SetSelectable(bool) to TextDocumentView.

HaikuDepot: React to B_SELECT_ALL in custom text view

Renamed HaikuDepot's home to haikudepot.

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