add an 'auto_sync' submit trigger to Field
cut the 0.7.20 release
add package data for applib
tidy up the observers
fix the mapped view example to use unicode strings.
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