Add mention of no-namevar errors, so Google is more likely to send folk to the right answer

Also, fix Nick's inability to count.
Guts/meta: Write down the way we do redirects
Bulk-remove an unneeded link to the old language guide from metaparameter reference

Submitted to Puppet core as commit 161dd2f9a280fb5fd9634385a4cb24a9b6fbf07e.
There was never any "more information" in it, I dunno why that link was there in
the first place.
Send all old language guide links to appropriate page of the language reference
Publish the language features history table as its own page

This was in the old language guide, and deserves to live on in an expanded form.
Delete the old language guide

301 laid down in commit a2746314ce9eba91aabfb3244b00b0b274acd9a2 in the
puppetlabs-modules repo.
Merge branch 'kill_language_guide'