This diff
- removes a bunch of unused includes in the GUI, adds some that are subsequently found missing elsewhere.
- alphabetic include order
- cpp files include their header first
- Fix lots of terrible whitespace for members.
- NULL -> nullptr
- Avoid std::map count call, since find!=end will finish more quickly (after finding the first item, if there is one)
- Remove an unused PSError
- Remove a comment in IGUIObject about children being deleted recursively that should have been removed in rP22943 / D2311.
- Remove some unneeded friend relationships