add multiple presets

[FWDekker]

users can currently configure MOMMY_COMPLIMENTS and MOMMY_ENCOURAGEMENTS to change what mommy will say. users who want a stricter, tougher mommy can thus configure mommy to do so by themselves, but I anticipate there will be a few categories of behaviour that many users will want. so why not add those to the default presets?

so, add a variable MOMMY_PRESET, which determines which preset is applied:

• if the preset is unset (or unknown), the default (current) sentences are loaded, and then the user's configured templates optionally override that
• if a preset is set (and exists), these override the user's configured templates (but not the *_CUSTOM variables, of course), since it does not make much sense to set both MOMMY_COMPLIMENTS and MOMMY_ENCOURAGEMENTS (unless a user wants to override only one of them, and use the other from the preset?)