Refactor: Check_Curs_Move (Issue: 1995)

[Todd-C-Goldfarb]

In an effort to address this issue link: https://github.com/diasurgical/devilutionX/issues/1995

Refactored lots of functionality out into helper functions in cursor.cpp, small tweaks, but no big change to logic This is my first ever pull request, hoping to just get a bit of practice before I make a bigger contribution! (Tips and suggestions would be much appreciated)

[Todd-C-Goldfarb]

PR updated for clang formatting and consistent reference variable syntax.

[AJenbo]

Thanks, I did a bit extra refactoring to change the code to use Point rather then int pairs, this also removed some redundant code.