Implement user defined color synchronization

[patateqbool]

There is no hook built-in for when an user is changing the color of a function/basic block/instruction. While the painter takes user-defined colors into account (basically saving it and restoring it when it needs to paint over it), it won't synchronized between users. This will require the patch engine to be implemented.

[NeatMonster]

I editing the issue description for clarity. This is totally related to issue #9.

[NeatMonster]

"We'll be added in IDA 7.2" - Hex-Rays support