Add support for the user to declare what sections in an ELF should be disassembled as data or code

[1superchip]

This would allow the user to decide which sections should be disassembled as what rather than disassembling based off of section flags and/or names since ELF files can have varied section names
A case was just fixed of the section ".vutext" being disassembled as MIPS assembly due to it having AX in the section flags which caused objects in data to have incorrect sizes because of branches that were created in ".vutext". This case could be fixed by the user declaring ".vutext" as data rather than MIPS assembly.
This would also allow the user to finetune which sections of an ELF are disassembled as code or data rather than spimdisasm determining what a section should be disassembled as by the name and section flags.