Summary:
Glorious, glorious man pages.
This changes a bunch of things that were hard to break up from the diff, so the
resulting diff is big.
Use `Cmdliner.Manpage` to format man pages (and also format a bit ourselves
since it is so stubborn).
As a bonus, introduce the following subcommands:
```
infer run ... # same as default mode with -- before
infer capture ... # -a capture
infer compile ... # -a compile
infer analyze ... # InferAnalyze
infer report ... # InferPrint
infer diff ... # this one is not new
infer clang ... # InferClang, not that you should use it
```
The man pages can still be improved a lot. Notable missing sections:
`ENVIRONMENT`, stuff about .inferconfig, some example usage, `DESCRIPTION`, ...
Reviewed By: jberdine
Differential Revision: D4921083
fbshipit-source-id: 9602230
Jules Villard
709376945f