This is likely the least used page of the tile inspector, since two things have been broken for months apparently.

- The checkboxes for the blocked edges weren't being positioned correctly
- Rotating a banner that has either 0 or more than 1 edges blocked, the blocked edges weren't updated correctly

This re-introduces the use of buffers to work around colours not being set properly.

For clipping strings, we also now manually invoke `gfx_clip_string` instead of relying
on `gfx_draw_string_left_clipped` to do it for us. The latter resets the current font,
meaning it prevents the use of `MEDIUM_EXTRA_DARK` bases. This issue should be addressed
in a later commit.

Enable more warnings in Xcode project

Add -Wlogical-op

Allows turning on -Wlogical-op

Mark unused arguments in the libopenrct2 project

- Print warning/error code in log message
- Remove attribute from Object::SetSourceGame which has a FIXME comment already instead

For dummy classes and functions with empty bodies I've only commented out the arguments, for all others I used C++17's [[maybe_unused]].

Fix missing field initializers

Allow scrolling on spinners/steppers

Clear the length of the sprite hash buffer. It was growing longer and longer every time the hash was calculated.

This commit tackles the more difficult-to-fix warnings that -Wmissing-field-initializers reported. I've compares the new tables in TrackData with the old ones through a script to make sure they are in fact the same.

It's possible that widgets are arranged in such a way that the roder of buttons matches the order of tool-size widgets or steppers. Now instead of just checking the types, also their content will be checked.

This makes scrolling work for the stepper widget, and overrides behaviour for scrolling anywhere else in the window.

Verify compilability of headers on Travis v2

This will skip linking step

Using approach described in
https://github.com/OpenRCT2/OpenRCT2/pull/7369#issuecomment-393973857
with updates to ease readability and maintenance.

Submitted as different PR, to keep history of the old approach.
Supersedes #7369.