Main changes:
- Consolidate scrollbar setup code, reducing replicated lines of code split across disparate gui elements.
- Rename m_Width to m_Breadth as m_Length/m_Breadth makes more sense, particularly for when we (finally) implement horizontal scrollbars.
- Rename the scroll_bottom and scroll_top attributes to something that should make it more obvious what they do.
- Consolidate two repeated code sections (including a magic 1.5) into a shared method.
Minor changes:
- Correct some spelling/grammar in comments.
- Change uses of "scroll bar" and "scroll-bar" to "scrollbar" for consistency.
- Update years on affected .cpp/.h files.
- Draw scrollbars on top of the background sprite of the gui elements, instead of underneath it
Note: The modifications to mainmenu.{xml|js} are for test purposes only and are not intended to be included when committed.
Note: I'm fairly inexperienced when it comes to c++ and so if I've made any rookie mistakes (or even not-so-rookie mistakes) I apologise. And tell me gently, please 😉.