FreeBSD compat

[BenWiederhake]

• use ${MAKE} instead of make in Makefile (duh! It's called gmake on FreeBSD, what did I expect?!)
• Fix tl-parser/portable-endian.h (oh god)
• Spin up CI on many more platforms
• Mention that FreeBSD people need to build with gmake, not make

Credits to Pavel Korsakov for finding and helping with most of these issues

[BenWiederhake]

State in 1.3.0:

• Fix tl-parser/portable-endian.h (still waiting on do a correct definition vysheng/tl-parser#12 to be accepted …)
• Spin up CI on many more platforms
• Mention that FreeBSD people need to build with gmake, not make, and that they have to apply above PR by hand