Add demangling and directive hiding for asm

[wfchandler]

Implements symbol demangling and the option to hide assembler directives (e.g. ".loc 2 338 0 prologue_end") from the generated assembly. Both options default to on and are editable using the Config dialog.

New - Demangled with Directives Removed:

playground::main:
	sub	rsp, 56
	lea	rax, [rip + ref.2]

Existing - Mangled with Directives:

	.text
	.intel_syntax noprefix
	.file	"playground.cgu-0.rs"
	.section	.text._ZN10playground4main17hf4c1d0e5656172f7E,"ax",@progbits
	.p2align	4, 0x90
	.type	_ZN10playground4main17hf4c1d0e5656172f7E,@function
_ZN10playground4main17hf4c1d0e5656172f7E:
	.cfi_startproc
	sub	rsp, 56
.Lcfi0:
	.cfi_def_cfa_offset 64
	lea	rax, [rip + ref.2]

[shepmaster]

Wow! Thank you so much; I know this is a feature that people have been wanting!

Does this work equally for AT&T and Intel assembly syntax?

[shepmaster]

Why is this needed?

[wfchandler]

I found that the background to the config popup would not fit the new rows, causing the "Done" button to be overlaid on top of the drop-downs as in issue #222. I should probably have removed the divide by $PHI as the golden ratio is pretty well shot by this change.

[wfchandler]

No issues with Intel vs AT&T, directives have the same format in both styles. The remove_assembler_directives function just searches for any lines that start with a period and excludes them from the updated string.

[shepmaster]

Oops, I guess I don't run these tests in CI at all! I should fix that...

[wfchandler]

On my local test sandbox::test::memory_usage_is_limited is failing with:

---- sandbox::test::memory_usage_is_limited stdout ----
thread 'sandbox::test::memory_usage_is_limited' panicked at 'assertion failed: resp.stderr.contains("Killed")', sandbox.rs:848:8

Not sure if that's a real issue, or just differences between the containers on my machine and production.

[shepmaster]

/cc #15

[shepmaster]

Wonderful, thank you very much!