NSBaseLineOffsetAttributeName support

[xmas79]

NSBaseLineOffsetAttributeName attribute support. Please review the code.

Thanks,
xmas79.

[codecov-io]

Current coverage is 100%

Merging #604 into master will decrease coverage by +29.77%

1. File ...TTTAttributedLabel.h (not in diff) was modified. more
   • Misses 0
   • Partials 0
   • Hits +2

@@             master    #604   diff @@
=======================================
  Files             2       1     -1   
  Lines           944      31   -913   
  Methods         112       0   -112   
  Branches        225       0   -225   
=======================================
- Hits            663      31   -632   
+ Misses          128       0   -128   
+ Partials        153       0   -153   

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[getaaron]

Thanks for the PR, @xmas79. Can you please add some automated tests to cover this change and I'll merge it in?

[xmas79]

Hello,
the ci/circleci tests failed because of:

Xcode version '6.3.1' is not available. Available versions are: 6.4, 7.0, 7.1
Action failed: Configure the build

I don't know how to proceed.

Thanks,
xmas79.

[mostinho7]

Thanks for the pull request @xmas79 I am using this in a project and it's causing me problems as well. I hope it gets merged in asap.
Thanks for TTTAttributedLabel @getaaron

[segiddins]

Circle has been fixed, but this still needs test coverage & a rebase to be mergable

[rickharrison]

Unless I am doing something incorrectly, it does not appear that this will offset any text above it. I.E. it will render on top of other lines of text if the offset is large enough.

[wildseansy]

@rickharrison - For my use case this is better than no support at all for NSBaselineOffsetAttributeName.

For the most part, I just want to adjust different font types slightly with respect to one another. For example an icon font placed next to some text, it's nice to vertically adjust the icon. Lines bleeding into one another could be a subsequent improvement, if there is a need.