Add semantic mods types

[eps1lon]

Adds support for selector mods that determine if a given mod belongs to a defined group.

Goal is to provide an api that is closer to the common usage of mods in the poe comunity while hiding implementation details of mods such as generation types and domains.

TODO:

• [x] elder/shaped mods
• [x] Master Signature mods
• [x] Bestiary Aspect mods
• [x] Warbands mods
• [ ] Essence mods (Essence item orb generator should be sufficient.)
• [ ] Master Crafted (#48)
• [x] Enchantments (see EnchantmentBench generator)
• [x] Corruptions (see Vaal generator)
• [x] documentation with examples
• [x] changelog entry

[coveralls]

Coverage decreased (-0.06%) to 95.111% when pulling b6c761110f3df2c9e70844118d1cd1c98b8e19b4 on feature-semantic-mod-types into 806409fbd07d16820aca08ee59c44f9edeeb64f3 on master.