Memory optimization

[srobotta]

Apparently the script needs quite a lot of memory. We have globally 128MB allowed for PHP processes. This used to be sufficient for the plugin.
Now in several places I get a memory exception and therefore a blank page. Unfortunately I have no stack trace. The log entry only contained the following:
Got error 'PHP message: PHP Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 65536 bytes) in /srv/moodle.bfh.ch/moodle/lib/mustache/src/Mustache/Cache/NoopCache.php(45) : eval()'d code on line 3'

A hot fix is to increase the memory in the report.php and view.php.