Fix notices of undefined variables inherited from BCU

[Jeremy Hopkins]

The following notices appear both in BCU and Adaptable:

Notice: Undefined property: stdClass::$enablealert1 in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 121

Notice: Undefined property: stdClass::$alerttext1 in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 122

Notice: Undefined property: stdClass::$contexturl in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 465

Notice: Undefined property: stdClass::$from in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 349

Notice: Trying to get property of non-object in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 364

Notice: Undefined property: stdClass::$from in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 373

Notice: Trying to get property of non-object in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 373

Notice: Undefined property: stdClass::$from in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 349

Notice: Trying to get property of non-object in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 364

Notice: Undefined property: stdClass::$from in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 373

Notice: Trying to get property of non-object in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 373

Notice: Undefined property: stdClass::$from in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 349

Notice: Trying to get property of non-object in C:\Moodle\moodlem2\theme\adaptable\renderers.php on line 364

[Jeremy Hopkins]

Fix #318 - catch notices from renderer caused by undefined variables

→ <<cset f2ca5aa05f9f>>

[Jeremy Hopkins]

Fix #318 and improves messaging which may help with #249 and #300

→ <<cset ab00bcee99dd>>

[Jeremy Hopkins]

Improve Fix #318

→ <<cset 5a6119eb8926>>