Issue 4868: Add limited embedding support for OpenType/CFF Collection (OTC) fonts

Issue 4868/2: Add limited embedding support for OTC fonts

  This commit adds limited embedding support
  for OpenType/CFF Collection (OTC) fonts
  which have `*.otc' filename extension.

  Essentially, the extension of OTC font files should be `*.otc'.
  However, most of the OTC fonts have the extension `*.ttc'
  for backward compatibility.
  https://www.microsoft.com/typography/otspec/recom.htm

  So this is limited support
  because most of the OTC fonts cannot be used.

  TODO: distinguish files which have extension `*.ttc'
  whether TrueType Collection (TTC) fonts or OTC fonts.

Issue 4868/1: Add font-index for embedding OTC fonts

  This commit adds support font-index
  for OpenType/CFF Collection (OTC) fonts
  not only TrueType Collection (TTC) fonts.

[lemzwerg, 2016-05-30 18:13:05]

LGTM, thanks!

[trueroad, 2016-06-06 13:58:24]

I've pushed to staging.

Issue 4868/1: Add font-index for embedding OTC fonts
commit 8d1f238d09ada2152baebdfc949b7f56c2e7bfd6

Issue 4868/2: Add limited embedding support for OTC fonts
commit 44802bfc4e5c3c03e675a83a5afe7ac99fb3b26d