Fix uninitialized variables, memory leaks

[Web-eWorks]

I've run AddressSanitizer, LeakSanitizer, and ThreadSanitizer on the code (as well as a brief pass with Valgrind) to clean up any possible issues or errors that might have been introduced without notice.

This PR fixes, in total:

• 1 read-past-end bug (in DistanceFieldFont.cpp)
• 2 uninitialized variable accesses (in scenegraph/Model.cpp and ship/ShipViewController.cpp)
• 3 memory leaks, of varying severity between a few hundred bytes and 600kb

[impaktor]

Could any of these explain some of the reported bugs on Lua side?
(Just checking if I should add a sub-routine to my brain when hunting reported bugs that says "this might have been fixed in master")

[Web-eWorks]

Very unlikely - these are all in C++. The only thing that even comes close to Lua memory was the LuaRef bug, and that was entirely benign other than leaking unused memory.