Does not compile with CoffeeScript 2.7.0

[lss4]

I tried compiling the engine with the CoffeeScript version I've installed on my system (2.7.0) and it's failing with this error in several places (combat.coffee, adventure.coffee).

See jashkenas/coffeescript#4752 for more info about this error. I think it was valid with CoffeeScript 1.x but now forbidden in newer ones due to it producing invalid JS in some cases.

Looks like the related code needs a refactor, but I'm very new to JS and CoffeeScript in general so I'm not sure which way will it produce JS that actually works...

EDIT: Newer CoffeeScript has deprecated the use of --join and a warning will be given for its usage. Changing the build command to use the suggested command pattern (cat a.coffee b.coffee c.coffee | coffee --compile --stdio > bundle.js) works fine here.

EDIT 2: Added some initial changes. These changes at least allowed the code to compile and work as expected. I'm currently playing through the demo game with the newly compiled JS and while there are some rough edges in the compiled code (like slightly altered variable names in some places), no gameplay misbehaviors or crashes have been observed so far.

EDIT 3: So far looking good. Was able to complete a playthrough of the demo game without any issue.