[FEATURE] Implement saves using binary files

[jgabaut]

Situation

At the moment the saving/loading is based on plaintext, which is obviously not the best but it gets the job done.

Steps

Relevant docs:

• handleLoadgame_Enemies()

• handleSave_Enemies()

• handleLoadgame_Home()

• handleSave_Home()

Useful links:

• How to write C structures to a file
• Usage of "packed" attribute for C structs
• Struct padding and packing

[jgabaut]

This was implemented as an experimental feature with 1.4.4. Closing this issue, a new one for refinements will be opened.