Use window.onerror instead of window.addEventListener for error trapping

Now the error trapping works in Firefox
Extend fieldmodules to include an "editType" field

This will allow us to provide the right HTML5 input element for things
like colours and dates
Improve handling of fieldmodules lacking a stringify method
Add input type handling to the texteditor

This allows us to customise the input element used for each field type.
The only one implemented at the moment is color, which currently only
works on Chrome
Simplify tag styling
Mute some of the tag colours