Withdraw support of SpiderMonkey generators

This removes the need for the ES6 check which uses eval and will not
work with a CSP.
No longer possible to run specs from raw.github

Due to introduction of build infrastructure.

Fixes #409
Emphasize error-handling and robustness

Fixes #406

Fixes #398
Merge pull request #414 from kriskowal/readme-406

Emphasize error-handling and robustness
Merge pull request #366 from kriskowal/no-spider

Withdraw support of SpiderMonkey generators
Change log: withdrew SpiderMonkey generator support
Merge branch 'master' into modular

Conflicts:
	CHANGES.md
	q.js