Centralize code for resource limit setting

Right now following code is copy-pasted in multiple places in In-Portal:

set_time_limit(0);
ini_set('memory_limit', -1);

I propose, that we can move it into a new function and use it instead in all places. Here are the benefits:

• it's auto-completed, so less chances to make typo error in setting name
• we can add parameters to it allowing setting custom memory & time limits
• we can easily track all code, that uses it to determine code, which heavily uses system resources