remove unused import
wip commit of expression engine refactor
add new supporting files for expression engine
wip update for new engine
update build script
remove unneeded files
add a c++ dynamic scope
add a 'dynamic_load' method to the CodeTracer
update imports
update standard handlers and operators

This updates the handlers to use the new C++ dynamic scope. The
operators are updated to suit.
WIP commit
start rewrite of compiler for updated operator engine
remove dead files
make distinction between module and expression nodes
make distinction between module and expression nodes
make read and write handlers public
use a scope key instead of a scope name

This is more flexible and eliminates the possibility of name clashes
with imported library enamldefs which are embedded in the widget tree.
update the compiler code generation
add a node class which stores the tree type structure
update compiler helpers for new compiler code gen