* Put all of TitleSequenceManager into the same namespace
* Move RideConstructionState into the OpenRCT2 namespace
* Adopt existing namespaces into OpenRCT2 namespace
This adds `using namespace OpenRCT2` to compilation units where appropriate,
as a means to get the codebase to compile until these units have been placed
in a namespace of their own.
- sprite building would save a file with just the sprite file header
and then immediately open it again at the beginning of compilation
- sprite file generation is now entirely in memory until the final
output file is saved on success
- added validation of no file activity in the failed build test case;
failed builds will not generate a file or edit an existing one
