Enforce statement

[hanjoosten]

Please support the ENFORCE statement.

[hanjoosten]

See AmpersandTarski/Ampersand#1204

[hanjoosten]

Current implementation is't correct. it gives:

Reproduction: In an .adl file, start a new line and start typing, EN. You'll see the ENFORCE statement comming up to be selected. Then select it.

[RieksJ]

I've updated the snippet so that it now supports Scenario 1, with SOMEKEYWORD replaced with ENFORCE. I might have (accidentally) updated the master branch again...