Rel vaddrs

[henrymkw]

This PR adds virtual addresses support for RELs splits.txt and symbols.txt files. This would resolve #98.

Implementation

The main implementation goal was make changes in the 'front-end' without touching the 'back-end'. Virtual addresses get converted to REL addresses upon parsing, which the REL address is used for the remainder of runtime. A virtual address field was also added to ObjSymbol to support virtual addresses in objdiff.

Usage

To use, the user needs to add the virtual_address:{offset_virtual_address} attribute to each section definition in splits.txt. For example

Sections:
	.text       type:code align:4
	.ctors      type:rodata align:4
	.dtors      type:rodata align:4
	.rodata     type:rodata align:32
	.data       type:data align:8
	.bss        type:bss align:32

Will become

Sections:
	.text       type:code align:4 virtual_address:0x805103B4
	.ctors      type:rodata align:4 virtual_address:0x8088F400
	.dtors      type:rodata align:4 virtual_address:0x8088F704
	.rodata     type:rodata align:32 virtual_address:0x8088F720
	.data       type:data align:8 virtual_address:0x808B2BD0
	.bss        type:bss align:32 virtual_address:0x809BD6E0

From here, the user needs to adjust the addresses in splits.txt, and the addresses and auto generated names in symbols.txt to be virtual.

Feedback

This is my first time writing Rust, so I'm sure there are some 'code smells' as a result; feedback related to that is greatly appreciated.

Other than that, I want to bring up requiring users to adjust addresses and names in symbols.txt and splits.txt themselves. I believe automating this through dtk is out of scope for this PR. It would require relatively significant refactoring and risks introducing breaking changes. I think requiring the user to make a script to make adjustments would be the best option for now.