1.2.1 - Bugfix update, mostly

New

• ImageHeader can now be created from arbitrarily values (ImageHeader.from_values())
• New Constructable LoadCommand + Segment currently used in tandem with old Segment wrapper.
• Unit tests!
• --fdec flag for dump, which forward declares private class imports

Fixes

• BytesIO fixes
• Fix lc insertion
• Fix with mmaped IO loader
• Program no longer crashes on unimplemented load commands
• Better VM segment input verification
• Properly null pad strings in structs
• Minor fixes in help messages
• Fix a crash with the codesign parser
• Fix (one) missing Chained Fixup structure.
• Fix relative method list parsing when relative addresses are negative
• Much better error handling in objc parsing
• Better info on bad load commands