quiz settings: MDL-18485 Improve quiz settings form

quiz settings: MDL-18485 Improve quiz settings form

* Reorder form fields to group things more logically.
** and on the corresponding admin page too.

* Set some options to be 'Advanced' by default:
** Apply penalties.
** Each attempt builds on the last.
** Decimal places for question grades.
** The five 'Extra restrictions on attempts' settings. (password, etc.)
* Admins can still change this to suit their institiution at Administration > Plugins > Activity modules > Quiz.
* These new defaults are applied if the admin had not previously set any fields to be advanced.

* Disable some filds when they are not applicable:
** Grading method, if num attempts = 1
** Penaly scheme, if adaptive mode = no
** Each attempt builds of last, if num attempts = 1
** Review after quiz closed options, if no close date.
** Delay between 1st and 2nd attempts, if num attempts = 1
** Delay between later attempts, if num attempts < 3

* Convert quiz.timelimit to be in seconds, for consistency, and ready for the new duration field type (MDL 18500).
** Including ensuring that backup and restore is backwards compatible.

* MDL-5537 New setting, questiondecimalpoints, so, for example, you can show the quiz grade as an integer, but have fractional question grades.
** There is a 'Same as overall decimal points' option, which is the default.

* Improve some field labels.

* Make corresponding changes in the help files.