Implement filters in blitz

[Pablete1234]

Fixes #365

Adds a filter attribute or child to blitz, if the filter denies, your life counter does not go down.

Example, you will only lose a life when dying after 30s from match start:

<blitz>
  <lives>5</lives>
  <filter>
    <time>30s</time>
  </filter>
</blitz>

Adding it as an attribute is also valid (note, the filter will have to be defined elsewhere):

<blitz filter="time-30-sec">
  <lives>5</lives>
</blitz>

[Electroid]

Sweet!

[Pablete1234]

This was a draft because i have done 0 testing on this feature so far