MDL-47613 wiki: allow searching several words

Thanks to Sandeep B for suggested solution
MDL-47646 CURL redirect unit test: handle broken servers
MDL-38732 gradereport_grader: Undefined variable in unit tests
Merge branch 'MDL-47646_26' of git://github.com/timhunt/moodle into MOODLE_26_STABLE
MDL-47431 advanced grading: correct use of frankenstyle names for consistency
Merge branch 'MDL-38732-26' of git://github.com/FMCorz/moodle into MOODLE_26_STABLE
Merge branch 'wip-MDL-47613-m26' of git://github.com/marinaglancy/moodle into MOODLE_26_STABLE