values implementation
Merge branch 'dev' of https://github.com/mickael-menu/libpirt into dev

Conflicts:
	Makefile
	include/commit.h
	include/pi_thread.h
	include/value.h
	src/commit.c
	src/pi_thread.c
	tests/channel_test.c
implemented some primitives on values
a test script in runtime_test.c
new value functions - invariant todo
Merge branch 'dev' of https://github.com/mickael-menu/libpirt into dev
minor corrections and adding some value functions
correction on value kind test
minor corrections
Refactor values and various corrections