Expand `let-alist' upon `sx-assoc-let' expansion
Fix `sx-assoc-let' tests

`require' form is no longer needed -- macro expansion is done with the
expansion of `sx-assoc-let'.
Merge branch 'master' into issue-151--dot-variables

Conflicts:
	sx.el
Merge branch 'master' into issue-151--dot-variables
Merge branch 'master' into issue-151--dot-variables

Conflicts:
	sx.el
Reapply ef1d321a157e300d29c48e461257897fca1c9aa4

It was somehow lost in the merging.
Test sx-assoc-let according to functionality

See http://emacs.stackexchange.com/q/5915/2264 and #151 for more
information.  This patch tests for functional equivalence rather than
symbolic equivalence.

Symbolic equivalence would be far preferable, but it does not appear to
be happening anytime soon -- perhaps when things settle down a bit for
the authors :)
Fix typo
Merge pull request #169 from vermiculus/issue-151--dot-variables

Fix dot-variable troubles