ASL with extensions

Extensions:

• Add fenced code block support
• Add named arguments and default arguments (this is a breaking change)
• Add asl_end_execution
• Add "x with { [2] = '1' }" to give the same expressive power that "x OR 0x4" gives you

Typechecker:

• Fix constraint inference on if statements and mutable variable declarations
• Error messages
• Improve monomorphization error messages

C/C++ backends

• Insert runtime bounds checks
• Support slices of integers - turns out they are important for FP code
• Optimize small integers in sc, ac and c23 backends (use -Obounded to enable this)

C23 backend

• integer promotion issues (that caused mis-compilation)
• asl_sub_bits was broken

SC/AC backends

• handling of INT_MIN values

Many minor bugfixes