Simplify CSS, bigger monospace to match math
Reducing overlap of code and math.

Prefer smaller islands of `code` in bigger
sections of $math$. Do not include $`code` in math$,
and avoid `$math$ in code`.
Minor typographical fixes for lexical syntax chapter
Don't mention C#
Merge pull request #3666 from adriaanm/spec

Spec cleanups
Disable more of the Travis spec build for PR validation

So as to avoid:

	$ ssh-add -D
	All identities removed.
	$ ssh-add spec/id_dsa_travis
	Enter passphrase for spec/id_dsa_travis:
	No output has been received in the last 10 minutes, this potentially indicates a stalled build or something wrong with the build itself.
Merge pull request #3664 from iainmcgin/lexicalfix

Minor typographical fixes for lexical syntax chapter
Merge pull request #3668 from retronym/topic/travis-ssh

Disable more of the Travis spec build for PR validation
Rebase #3665
Merge remote-tracking branch 'upstream/master'