* Fixes for many low-severity compiler warnings
Mostly a lot of pedantic things like end-of-file newlines and commas on the last enum value. However some fixes like the weak v-tables warnings fixes might help with code gen. It's unclear if the linker is able to elide multiple copies of the same type's v-table in different translation units, (sometimes it can) but these fixes ensure we don't have to rely on it.
This changes dtTileCache::update to add an optional parameter that
indicates whether the tile cache is up to date. This is useful to
determine whether calling the function again would do anything.
* Added virtual qualifier to a few destructors in subclasses.
* Removed a few empty destructors that didn't need to be explicitly defined.
* Fixed a few typos
* Removed unnecessary empty virtual destructors in some classes with parent's who derrived from a class with a virtual destructor
