Add -XImportHook= mechanism for custom importers
Change default method visibility to public
Update default visibilities in JS UI
Make "done" call itself such, not "noSuchValue"
Support and expose "unbecome" primitive
Update JS UI to display only one of code/output at once
Make code/output textareas occupy the available space
Include match method on all blocks in JS
Delete gracelib-basic.o in make clean
Abstract object header to #define to allow changes
Copy samples into tarball
Add support for -XPlugin= compiler plugins
Handle MPMN parts with no arguments correctly
Tell typechecker about String.encode method
Add set difference - op to mgcollections
Handle outside operators with unknown definitons

Previously, the compiler would crash when an operator defined in another
module was used, because it expected to be able to see the parameter
types fully.
Allow references to defs in their initialisation
Remove obsolete tests
Apply small bugfixes revealed by IDR
Add first pass at identifier resolution phase