Saturn workflow improvements

[sozud]

• make build not require rm -rf each time
• Allow renaming functions before decompiling
• Use a disk rather than copying files to dosemu (see Copy a bit less stuff when using dosemu decompme/decomp.me#1423)
• Do a better job of propagating function labels to the disassembly in saturn-splitter

[Xeeynamo]

• Doing make -j build does not work well like on PSX, causing a slower feedback cycle for local decomp
• The .data section on a compiled C object is ignored. This does not allow to import data
• Needing of a stronger pointer detection when disassembling with saturn-split
• Better diff-ing on the section after a rts
• Allow to forcefully define symbols to guide the disassembler on how to correctly split functions that cannot be detected