Add map_element_height (finishes sub_662783)

Possibly wrong for some slopes...
squash! Add map_element_height (finishes sub_662783)
Change formatting to VS style, improve comments
add load game and landscape dialog
Merge branch 'element_height' of https://github.com/ZedThree/OpenRCT2 into ZedThree-element_height
remove unfinished comment and credit author
Merge branch 'ZedThree-element_height'
Merge remote-tracking branch 'refs/remotes/upstream/master'

* refs/remotes/upstream/master:
  remove unfinished comment and credit author
  add load game and landscape dialog
  Change formatting to VS style, improve comments
  squash! Add map_element_height (finishes sub_662783)
  Add map_element_height (finishes sub_662783)