Purge Continue from the language

This was just a bad idea. It's needlessly complicated and not terribly useful.

Change-Id: I30d96d968066c4d15cda994fe9a1be368ec18c5f
Add debugging output to bootstrap interpreter

Change-Id: I3283d6e27de78c31c9b9a557d193c59900e0cfeb
Fix spelling of environment

Change-Id: I2f1f90857407c501eafc794bb213fe82f095f993
Factor our common compare_operator template

Change-Id: I7f39317301f44a63dcd8d9330c574ae7df240539
Fix parsing errors

This removes spurious arithmetic conjunction/disjunction nodes and makes Select expr check there is no colon, but it tends to eat the next attribute's comment

Change-Id: I296024b98dda91d030f99cccd4e9047a518f7e67
Improve generated code and parsing data

Original file positions were not being put in the AST nodes and some fields were being copied twice

Change-Id: I3ff1d62ddcc7643c94a6bed22da53b2577771d99