[stack.defn] Fix swap signature.

Reported by Stephan T Lavavej. Fixes #242
[futures.overview] Add ArgTypes... to swap declaration.

Fixes #336
[func.bind.bind] Fix "template parameter back" typo.

Fixes #316
[memory.syn] Change "template functions" to "function templates"

Fixes #302
Merge pull request #354 from jwakely/issue-242

[stack.defn] Fix swap signature.
[utility] Add index_sequence et al to the library index.

Addresses #245