More rigorous linting

[twpayne]

This PR activates the --jslint_error=all flag to gjslint and fixes all the problems it finds.

[fredj]

LGTM

[tschaub]

Looks good. I use another linter that I think will start complaining about side effects in the tests, but I'll see about making them both happy.

[twpayne]

I also use jslint in my editor which complains about using new for side effects, so I'll find a way to write the tests that satisfies both jslint and gjslint.

Note that this PR depends on #740.

[twpayne]

I use another linter that I think will start complaining about side effects in the tests, but I'll see about making them both happy.

I've now fixed this and updated the PR. The fix was, instead of writing:

new X(); // jslint issues WARNING:Do not use 'new' for side effects.

I've used:

var x = new X();
x = x; // suppress gjslint warning about unused variable

This passes both gjslint and jslint. Only code in the tests is affected.

[elemoine]

Very nice Tom! Thanks.