Add example of Macro.var/2 to Meta guide

Since var!/2 no longer accepts atoms directly, Macro.var/2 is recommended.
Merge pull request #287 from hamiltop/master

Add example of Macro.var/2 to Meta guide
Release v0.14.2
Remove mention to deprecated size/1
Update 12.markdown
Minor touchups to Mix and OTP Chapter 4
Merge pull request #288 from ernie/otp-chapter-4-touchups

Minor touchups to Mix and OTP Chapter 4
Fix "spawning" instead of "spanning"
Merge pull request #289 from trapped/patch-1

Fix "spawning" instead of "spanning"
Fix "behavior" instead of "behaviour"
Merge pull request #291 from trapped/master

Fix "behavior" instead of "behaviour"
Clarifications and touchups to Mix/OTP Chapter 5
Merge pull request #292 from ernie/otp-chapter-5-touchups

Clarifications and touchups to Mix/OTP Chapter 5
Remove spaces in tuples and use String instead of Regex
Another attempt at getting highlight right
Minor touchups to Mix and OTP chapter 6.

An important one is removing the potentially-confusing use of the word
"global" when referring to table names. While they are "global" in the
sense I, as a Rubyist, might think of "global", they are "local" in
terms of Erlang name registration, and other nodes can't see them.
Merge pull request #293 from ernie/otp-chapter-6-touchups

Minor touchups to Mix and OTP chapter 6.
Update 5.markdown

Looks like "not" is missed?
Merge pull request #294 from cris/patch-2

Update 5.markdown
Fix display of {{ in code examples