MDL-39871 themes: can now specify regions to swap when using rtl langs
MDL-39841 renderer: new method to renderer blocks with predictable structure
MDL-39838 renderer: new methods for body classes and id
MDL-39839 renderer: new methods for  calls appearing in theme layouts
MDL-39824 output: tidied up output before bootstrap cleaning
MDL-40089 theme_bootstrapbase: moved general to columns3.php as prep
MDL-39824 theme_bootstrapbase: converted $PAGE use to new $OUTPUT methods.
MDL-39842 js: fixed block drag and drop
MDL-40089 theme_clean: moved general to columns3.php as prep
MDL-40089 theme_clean: simplified layouts and converted to new OUTPUT API