ARMv5TE (DS) support (#68)

* Initial ARM support

* Disassemble const pool reloc

* Disasm ARM/Thumb/data based on mapping symbols

* Fallback to mapping symbol `$a`

* Support multiple DWARF sequences

* Update line info

* Rework DWARF line info parsing

- Properly handles multiple sections
  in DWARF 1
- line_info moved into ObjSection
- DWARF 2 parser no longer errors with
  no .text section
- Both parsers properly skip empty
  sections

* Simplify line_info (no Option)

* Get line info from section; output formatted ins string

* Unwrap code section in `arm.rs`

* Handle reloc `R_ARM_SBREL32`

* Update ARM disassembler

* Update README.md

* Format

* Revert "Update README.md"

This reverts commit 8bbfcc6f45.

* Update README.md

---------

Co-authored-by: Luke Street <luke.street@encounterpc.com>

objdiff-core/src/arch/mod.rs

@@ -8,6 +8,8 @@ use crate::{
     obj::{ObjIns, ObjReloc, ObjSection},
 };
 
+#[cfg(feature = "arm")]
+mod arm;
 #[cfg(feature = "mips")]
 pub mod mips;
 #[cfg(feature = "ppc")]
@@ -46,6 +48,8 @@ pub fn new_arch(object: &object::File) -> Result<Box<dyn ObjArch>> {
         Architecture::Mips => Box::new(mips::ObjArchMips::new(object)?),
         #[cfg(feature = "x86")]
         Architecture::I386 | Architecture::X86_64 => Box::new(x86::ObjArchX86::new(object)?),
+        #[cfg(feature = "arm")]
+        Architecture::Arm => Box::new(arm::ObjArchArm::new(object)?),
         arch => bail!("Unsupported architecture: {arch:?}"),
     })
 }