run.dlang.io can now display ASM + AST + IR

[Seb]

It was bad weather in Munich on Saturday, so run.dlang.io got a 
couple of new cool features:

1) Assembly output

https://run.dlang.io/is/qtk8Wq

However, if you are seriously interested in looking at the ASM 
output, I recommend https://d.godbolt.org for LDC and GDC.

2) AST of DMD frontend (after semantic analysis)

https://run.dlang.io/is/TAHzMZ

Permanent: `-vcg-ast`

3) IR (LDC only)

https://run.dlang.io/is/BOTNDf

Might come to DMD, see https://github.com/dlang/dmd/pull/4972

4) Permanent flags

In case you want to share a link to someone and they should 
immediately see this, simply add the respective flag:

ASM: -asm (DMD) | -output-s (LDC)
AST: -vcg-ast
IR: -output-ll (LDC)

run.dlang.io is smart enough to display the resulting file.

5) Stores the latest source file in the persistent localStorage 
of your browser
6) Small UI updates

Any ideas?
-> https://github.com/dlang-tour/core/issues/new

Don't like the UI?
-> https://github.com/dlang-tour/core/blob/master/views/editor.dt