asm: added `global' instruction (doesn't work yet)
test: slight refactoring; added base test for global labels
mask: raise MaskNotFound instead of returning False
mask: AmbiguousMaskError is subclass of MaskNotFoundError
block: added Block.apply (wip, unneeded)
Revert "block: added Block.apply (wip, unneeded)"

This reverts commit 5753d1848579207ca5b9c311b5025373b9b751ec.
block: added getCode()
block: added getMask, getPosition
added Patch class & module
patch: added context and library properties
asm: I.findLabel: support patch-level and library-level global labels
patch: converted blocks to r/o property
Use Patch object everywhere where needed
parser: removed testing lines

They were implemented in test_parser
parser: implemented #include (not tested yet)
test_parser: added print stmt