readme.md: Change all Gittip links to Gratipay, as they changed their name
DataTables: Update all translation files for the new parameter names in DataTables 1.10 as well as for their content, from https://www.datatables.net/plug-ins/i18n/.
Use tabs for the whitespace in the JSON files, as we can replace those easily to minify the JSON code when loading a language into a page.
Translations: Rename locale abbreviations for Ukrainian (from uk_UA to uk), Latvian (lv_LV to lv), Belarussian (be_BY to bel), and Irish (ga_IR to ga), according to the locales as they are used in WordPress, see http://wpcentral.io/internationalization/.
DataTables: Add translations for Azerbaijani (az), Persian (fa_IR), Latvian (lv), Macedonian (mk_MK), Slovenian (sl_SI), Albanian (sq), Thai (th), and Vietnamese (vi), as there are WordPress versions for these languages. For Latvian, there's also a translation for TablePress already. Source for the translations: https://www.datatables.net/plug-ins/i18n/
Update the instructions in the warning about not directly changing the DataTables language JSON files.
DataTables: Add/fix "decimal" and "thousands" parameters in the DataTables JSON translation files, which are used for the type detection and sorting by DataTables. Information from http://en.wikipedia.org/wiki/Decimal_mark
Default CSS: Reset the `float` property for all table cells, and not just the last column, as there are more and more reports about issues where themes e.g. set a `float` on CSS classes like `.column-1`, etc.
Rendering/Default CSS: Remove the wrapping <div> containers in the header row cells that were used to add the sorting arrows via an icon font. Instead, load the icons directly in the :after pseudo-element of the cells.
Also, move all three icons up 1 pixel to vertically center them.