Add optional system of Preset Cultures

[Goosius1]

Description:

• This PR adds a new optional feature called "Preset Cultures".
• Preset cultures are defined in the config file. Each has a name and description e.g.

• If the feature is enabled, towns without a culture get an automatically assigned one, using one of two server chosen methods: random or location based.
• If the feature is enabled, mayors do not necessarily get the permission to set town culture, but if they do, they can choose only from the given list.

---

New Nodes/Commands/ConfigOptions:

  # +------------------------------------------------------+ #
  # |                    Preset Cultures                   | #
  # +------------------------------------------------------+ #
  
  preset_cultures:
  
    # If this value is true, then Preset Cultures are enabled.
    enabled: 'true'
  
    # This value affects how preset cultures are automatically selected for towns. Allowed values:
    # RANDOM = If town does not have a preset culture, one is selected at random.
    # LOCATION = If town does not have a preset culture, one is selected based on town location.
    automatic_culture_selection_type: LOCATION
  
    # The list of preset cultures.
    list: '[-20000, -20000], [-6667, -6667], North-Western, The people of the North-West are scavengers and traders. | [-6667, -20000], [6667, -6667], Northern, The people of the North are peaceful farmers. | [6667, -20000], [20000, -6667], North-Eastern, The people of the North-East are savage and warlike. | [-20000, -6667], [-6667, 6667], Western, The people of the West are ambitious empire builders. | [-6667, -6667], [6667, 6667], Central, The people of the Center are hard working industrialists. | [6667, -6667], [20000, 6667], Eastern, The people of the East are skilled merchants. | [-20000, 6667], [-6667, 20000], South-Western, The people of the South-West are peaceful and spiritual. | [-6667, 6667], [6667, 20000], Southern, The people of the South are barbarous and isolationist. | [6667, 6667], [20000, 20000], South-Eastern, The people of the South-East are polite and diplomatic.'

---

Relevant Issue ticket:

Closes #24
Closes #47

---

• [ x ] I have tested this pull request for defects on a server.

By making this pull request, I represent that I have the right to waive copyright and related rights to my contribution, and agree that all copyright and related rights in my contributions are waived, and I acknowledge that the TownyAdvanced organization has the copyright to use and modify my contribution under the Towny License for perpetuity.