Jarcast's Volcanoes for VP 6

Changelog:

• removed existing eruption events from base VP
• added 2 custom events (normal eruption and heavy eruption, the latter has less probability to happen), each with 2 choices. The first choice gives some Science (scaling with era) but the improvements adjacent to the Volcano are pillaged, there's a chance buildings are destroyed and interested City loses 3 citizens (5 in case of heavy eruption). The second choice unlocks when the City constructs the Volcano Observatory building: the effects are the same except Science yield is increased and City loses no population (the logic is the Observatory catches warning signs of volcanic activity allowing people to safely evacuate in time but buildings and improvements are still affected).

Improved the efficiency of Volcano placement algorithm, that is faster map generation.

Added a restriction to avoid spawning Volcanoes on hill natural wonders like the Barringer Crater.

Both mods add Obsidian resources but Volcano mod omitted the placement parameters for the resource and this created a bug whereby no resource spawned on the map.

Obsidian cannot spawn on city tile anymore.

Fixed volcanoes not blocking sight of the tiles behind, added value of SeeThrough column similar to Krakatoa, Sinai, Kilimanjaro, etc.
Thanks to @Flamingcheesepie for reporting.

Changelog:

• Fixed Obsidian Works not spawning Obsidian.
• Also reduced JAR_VOLCANOES_PERCENT from 25 to 10.

Changelog:
- fixed Volcano spawning on the same tile of a settler (very very rare but it could happen, now it never happens);
- added a lua workaround whereby tables Belief_CityYieldPerXFeatureTimes100 and Building_YieldPerXFeatureTimes100 give yields based on numbers of Volcanoes within 3 tiles without needing to work the tile, like it already happens with mountains (and mountains alone have such exception).
The bonuses appear as additional yields from buildings.

Changelog:
- fixed bug whereby Volcanoes spawn on Ancient Ruins;
- Natural Wonders Fuji, Krakatoa, Kilimanjaro count as Volcanoes for building requirements. If More Wonders for VP is enabled, also Mt. Paektu and Dallol.