waf: add verm's wscript
waf: add vim syntax comment
waf: use LF line endings
waf: change vim modeline to ft instead of syntax
waf: reformart wscript

OCD wouldn't let me touch it
waf: remove load of cxx compiler
waf: remove some OSX options which are no longer used
waf: remove `--cc` since the waf way seems to use CC env var
waf: name a hack
Fix detection of pkgconfig.
Remove unneeded hack.
waf: fix generation inout_conf.h
waf: compile in libass support

Also fix the ordering of the compilation of the `sub` target's source to
alphabetical order to keep it more tidy.
waf: move resampler detection to separate waftool
waf: remove ad.c
waf: move libav checks to their own file

Also create a pkgconfig file with some pkgconfig utility functions. I tried to
use a functional approach using list comprehensions and I'm happy with the
result being a little more declarative. I'll try to use something similar for
all the rest.
waf: refactor generic pkgconfig check to use utility function
waf: move configure variable mapping to a tool
waf: add libavfilter and libavdevice ldflags
let's try this again... and again, and again.