Learning Plan - Fixes for errors, added multi-language support, resolved...

... Moodle 2.6 compatibility issues

Changes include:

* Added security to ajax_bridge.php.
* Added security to student/view.php.
* All text appearing in the Learning Plan plugin uses text from the plugins language file to support additional languages. There is no longer any hard coded text in the source code.
* All user entered data now supports entry of multilang markup, accented characters and is filtered through filters before it is displayed. (tested with a French language file).
* A French language file is now included. Translation has started but is incomplete. The parts which are yet to be translated only affects administrative tasks.
* Upgrading the plugin triggers a clean-up of unused records in the learning_user_trainingplan table that were left behind when training plans were deleted. Change is in db/upgrade.php. *See Note (1)*.
* The learning_user_trainingplan table is now getting cleaned-up when removing a student from a learning plan. This issue resulted in many rows in the table that were no longer of use.  Change is in the delete_learningplan_record() function, learning_user_learningplan  section, the second use of the $DB->delete_records() function. *See Note (1)*.
* Adding a Learning Plan to a student now automatically sets the status to Not Yet Started by default. It was doing this before but storing it as text instead of a numeric value causing incorrect display of information.
* Sometimes status was stored in database as string and other times as a numeric value. It is now always stored as a numeric value. All, not just some, of the statuses now appear in the status column of the search results
* The 3 statuses levels are now defined in the language file for easy translation and modification instead of being hard coded throughout the source code.
* Upgrading the plugin triggers fixing inconsistencies of existing table records in learning_user_trainingplan table where text had been stored instead of numeric values for status. The mix of text and numbers resulted in some inconsistent operations.
* When viewing a training plan as a student, a Moodle warning was displayed indicating that the context was not set. Require_login() and $PAGE->set_context() have now both been added to student/view.php to fix the issue.
* Removed grey header table/box and re-formatted header in student/view.php so that it conforms to Moodle theme colour and formatting. The header is now also WCAG 2.0 level AA compliant.
* Added viewpage parameter to $PAGE->seturl() in view.php so that toggling of page language now works properly.
* Added id parameter to $PAGE->seturl() in student/view.php so that toggling of page language now works properly.
* Added link to breadcrumb in student/view.php so that the page's H1 heading appears correctly instead of just "My Page" or “Home”, depending on how you’ve configured Moodle.
* Applied Moodle's userdate() function everywhere date/time is displayed to format these in user local time and format defined in core_langconfig language file. The result is consistent date formats used throughout the Moodle site. You can customise these by modifying the Moodle language strings and resetting the cache. The original values are left in source code comments in case someone wants to know what the original values used to be.
* Removed duplicate string definitions in the language file which were leading to confusion (changes to a string and it wouldn't change because it was defined a second time elsewhere)
* Course names in the Student Status Report (student view.php) are now links if a URL is available.
* Some minor code cleanup including: corrections to source code indentations, replacement of tabs with spaces, removal of trailing spaces.
* Corrected typo in readme.txt file.

*Note (1) - IMPORTANT*: I am not 100% familiar with the way this table operates and would appreciate it if you would be so kind as to validate the effects of the code for the above two changes to ensure that they result in the desired outcome which is to prevent the accumulation of orphan table records.

Affected files include:

* ajax_bridge.php
* block_learning_plan.php
* learning_plan_form.php
* lib.php
* readme.txt
* version.php
* view.php
* db/update.php (new)
* lang/en/block_learning_plan.php
* lang/fr/block_learning_plan.php (new)
* student/view.php

Signed-off-by: Michael Milette <michael.milette@instruxmedia.com>