Make CI_Input::set_cookie() and cookie helpers set_cookie(), get_cookie(), delete_cookie()'s first (name) parameter mandatory
Make CI_Form_validation::error()'s first parameter mandatory and add a typehint for CI_Form_validation::error()
[ci skip] Fix a docblock typo
Make CI_Loader methods library(), driver(), vars() and language()'s first parameters mandatory and fix a docblock
Make CI_Session's set_userdata(), set_flashdata(), set_tempdata(), unset_userdata() and unset_flashdata()'s first parameter mandatory
Remove redudant Loader tests for library() & driver() with no parameters
Fix #2579: Query Builder's "no escape" functionality didn't work properly with query cache
Remove a redudant value check
Fix #2237: Parser library failed if the same tag pair is used more than once within a template

(manually applying PR #2238 + updated unit tests)
Add Basic HTTP authentication support to the XML-RPC library

(based on PR #1716)
Fix #2268 (manually implementing PR #2269)
Implement Loader method chaining

Requested in issue #2165
Supersedes PR #2319
Fix #2143

When trying to load rules from a configuration file, the Form validation library matched against
ruri_string() as opposed to 'controller/method' like described in the manual. Since ruri_string()
also makes sense, now both are being checked with ruri_string() having a higher precedence.

Supersedes PR #2224
Add ability for changing the original file path/name in CI_Zip::read_file()

Supersedes PR #884
Change Text helper default tag from <strong> to <mark>

Supersedes PR #1497
Update Text helper highlight_phrase() tests and add one for custom tags
Add a more clear note about query builder caching (issue #2721)
A tiny regexp improvement for CI_DB_driver::is_write_type()
Fix a few bugs in CI_Hook (based on PR #2762)