Usage of size_t for file addresses by LibGens

[NotKit]

LibGens and namely LibGens::File class use size_t type for reading/writing addresses stored in files.
size_t is unsigned int on 32-bit systems, but for 64-bit ones it is unsigned long int (8 bytes). This breaks code portability.
readInt32A and readInt32BEA, as well as corresponding write functions, are supposed to always read 32-bit value even on 64-bit systems for file formats compatibility. There are different ways to approach this, and I'm not sure what would be the correct one.

1. Replace size_t by unsigned int where needed. This should be save as long as it's used for file offsets, and not for memory pointers, but might require a lot of code edits.
2. Introduce a custom typedef for unsigned int. The rest is the same as first.
3. Modify read functions to ensure they always read 4 bytes and then properly put them into 8 bytes size_t variables, as well as do the opposite to write. The easiest, but seems like a hack to me.