Use lexical-binding in glasses.el and add tests

Use lexical-binding in glasses.el and add tests

* lisp/progmodes/glasses.el: Use lexical-binding.
(glasses-separator, glasses-original-separator, glasses-face)
(glasses-separate-parentheses-p)
(glasses-separate-parentheses-exceptions)
(glasses-separate-capital-groups, glasses-uncapitalize-p)
(glasses-uncapitalize-regexp, glasses-convert-on-write-p): Remove
redundant :group args.

* test/lisp/progmodes/glasses-tests.el: New file with tests for
glasses.el.