Fix PHP strict errors.
OU-3725 Fixing problems with answer tolerance when answer is negative
Merge branch 'PHILS_NEW_BUGS_21' into PHILS_NEW_BUGS
OU-3726 Fixed checking of sig figs
Merge branch 'PHILS_NEW_BUGS_21' into PHILS_NEW_BUGS
NOBUG unit tests to check grading of responses with wrong sig figs
NOBUG answer was being rounded before comparison to response

OU Bug 3728
NOBUG fixed grading of multiple tries at a question

OU BUG 3916
NOBUG tighten up the validation of the form

to not accpet rubbish in the 'error' field when the answer is '*'
Merge branch 'PHILS_NEW_BUGS_21' into PHILS_NEW_BUGS
Updated the delete_question function to work with MySQL
Merge branch 'PHILS_NEW_BUGS_21' into PHILS_NEW_BUGS
NOBUG warnings for users who enter units but ignoring them in grading

also improved response validation
Merge branch 'PHILS_NEW_BUGS_21' into PHILS_NEW_BUGS

Conflicts:
	lang/en/qtype_varnumericset.php
NOBUG changed unit tests to use PHPUnit
NOBUG fixing problems identified by Tim in his code review

https://github.com/moodleou/moodle-qtype_varnumericset/pull/4/files#r1002529
NOBUG refactoring response grading and validation as suggested by Tim
Merge branch 'PHILS_NEW_BUGS_21' into PHILS_NEW_BUGS
NOBUG fix error in the code for checking response for a valid number
Merge branch 'PHILS_NEW_BUGS_21' into PHILS_NEW_BUGS