Basic analysis of window_map_mousedown

* This function doesn't appear to relevant for the normal map window, as
it doesn't have the required widgets. Considering that the Scenario
Editor has a more complex map window, I assume that this function does
processing referred to that instance instead.
start implementing window_track_place
implement window_track_place_toolupdate
Still searching for bug
Started reverse of load_object
Added more of object load. Remember to change the openedEntry code
Still trying to find bug
Added a fixed version of read_chunk requires more testing before joining
Fixed remaining bugs caused by not using rct2 malloc.
Cso now partially working.
Integrated fix of read chunk into main code
Removed redundant function
Switched to main version of chunk read.
Switched to main version of chunk read.
Small refactoring of load packed
Added more of load packed
Added code for finding next avaliable file name
Added code for writing new packed file.
Fix travis errors
Added start of sawyer write chunk