ensure we are calling for python2
create a renderer to handle C language template

preliminary work to handle different language as targets
use the C library parser for yaml

Way faster parsing.
Add yamlc option to use the faster C loader

Some architecture don't have it, so it's off by default.
[fix] don't force little endian, instead detect it

Only works for gcc, should be easy to extend on the spot.
[fix] fix warnings about printf
add sequential target

Useful for speedup baseline comparisons for example.
Generate a copious amount of useless function call though, smart compilers
should deal with it ok.