#### Brief overview of PR changes/additions
For drawing custom lines you can snap to grid all it's points + you can
move last point directly onto target room
#### Motivation for adding to Mudlet
I always found not perfectly angled lines to be bothersome, now it's
possible to easily achieve perfect lines between rooms.
#### Other info (issues closed, discussion etc)
<!-- Keep the title short & concise so anyone non-technical can
understand it,
the title appears in PTB changelogs -->
#### Brief overview of PR changes/additions
Remove support for leak detection using MSVC - this functionality hasn't
been in use in a decade, and we're switching to to using
[LeakSanitizer](https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer)
instead.
#### Motivation for adding to Mudlet
Cleaner code.
#### Other info (issues closed, discussion etc)
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Co-authored-by: Claude <noreply@anthropic.com>
#### Brief overview of PR changes/additions
When refactoring handlers accidently broke add/remove point on custom
lines, this restores this functionality
#### Motivation for adding to Mudlet
Fix :)
#### Other info (issues closed, discussion etc)
#### Brief overview of PR changes/additions
I split mouse interaction logic into separate small handlers, that are
checking whether they can act on interaction in priority order.
There is separate struct that is responsible fore keeping current map
interaction context, that is used by the handlers.
Solution might not be perfect at the time, but it is first step to
improving quality and consistency of interactions with map interface.
Deleting label clears it's selection state, since now if you delete
label and right click, you will still see context menu for that label.
There are some improvements in map interaction to be more intuitive.
Right click now will select room/label that is clicked.
Right click anywhere will deselect room and bring general popup menu.
Rectangle selection with shift will add elements to list.
Rectangle selection with ctrl will flip elements selection.
#### Motivation for adding to Mudlet
Code easier to comprehend, allowing further changes and fun additions,
like room link tool.
More cosistent and more intuitive way of map interactions.
closes#6033
