Merge https://github.com/privat/nit into string_refactor

Conflicts:
	lib/standard/standard.nit
	lib/standard/string.nit
	src/compiling/compiling_global.nit
	src/literal.nit
	src/metamodel/inheritance.nit
	src/metamodel/partial_order.nit
	src/metamodel/static_type.nit
	src/ni_nitdoc.nit
	src/nitdoc.nit
	src/primitive_info.nit
	src/syntax/icode_generation.nit
	src/syntax/mmbuilder.nit
	src/syntax/syntax.nit
	src/utils.nit
	tests/sav/test_isa.sav
	tests/test_eq.nit
	tests/test_eq2.nit