Merge pull request #61 from serpro/master

Allow URL links to have non-url text
Allow URLs without a protocol
6.4.0
Add relative and absolute URL support [#62]
6.4.1
Refactored tests for the CensorHook class

Try to make more accurate tests.
The equivalent censored contents and number of letters are tested.
Merge pull request #64 from alquerci/censor_hook.refactor_tests

Refactored tests for the CensorHook class
Don't trim spaces within tags [#63]
Added hhvm support
6.4.2
Reset errors [#65]
Update copyright years
6.4.3
Added colspan and rowspan support for [td] tag
Added colspan and rowspan support for [th] tag
Renamed colspan, rowspan to cols, rows
Merge pull request #66 from hilobok/master

Added colspan and rowspan support for [td] tag
Add a filter aliasing system
Improve filter efficiency by compiling tags during construction
Improve test code coverage
Add aliasing for attributes