v3.1.0-rc4

Changes from v3.1.0-rc3:

1. Previous progress detection improvements
2. Various logging improvements and utilising a progress log.
3. Git repos stored in user cache dir to prevent unnecessary deletion on system restart.
4. Version and build control moved to Makefile
5. Unnecessary folders no longer created in working dir (hangup from older versions).
6. Much improved container handling and detection of already built containers (even rebuilding with cache is slow so avoiding that if possible).
7. Various misc QoL for outAsDir.
8. Some manual garbage collection triggering to attempt to reduce memory usage by some non-zero amount when looping through slices etc.