Riscemu

- Syscalls: cleaned up formatting and added instructions for extensions
- Parser: fixed error when labels where used outside of sections
- Cleaned up and improved memory dumping code
- Fixed a bug with hex literal recognition in instruction parse code
- Fixed bug where wrong parts of section would be printed in mmu.dump()
- Removed tests for bind_twos_complement as the function is now redundant with the introduction of Int32
- Fixed address translation error for sections without symbols
- Changed verbosity level at which start and end of CPU are printed, added prints for start and stack loading

- Added implicit declaration of .text section when a file starts with assembly instructions without declaring a section first
- Fixed a regression where the cpu's exit code would no longer be the exit code of the emulator. Now the emulator exits with the cpu's exit code
- Added the changelog

- Fixed type annotations in parser code that prevented running unprivileged code

- Correct handling of 32 bit overflows and underflows
- Complete revamp of internal data structures
- Completely reworked how assembly is parsed