Expanding custom events and custom messages

[UberWaffe]

Proposed features (in no particular order):

• Remove old demand changes code. Replace editor UI with similar look but that creates events in the background.
• Add event chains.
• Rework custom events UI editor to show text instead of numbers, and have descriptions.
• Sort event actions and conditions lists alphabetically.
• Add way to use a custom message as the defeat message in a scenario, overwriting the default if provided.
• Add way to use a custom message as the victory message in a scenario, overwriting the default if provided.
• Add triggers to events. (Currently all events have only one hardcoded trigger, which is start of a new month.)
• Allow scenario event to have a name and tag.
• Add way to enable and disable other events. (i.e. I want an event to be completely inactive until enabled by another event, or vice versa. Should allow for a 'tag' to be added to events, and the enable / disable to be done on a tag level (i.e. one or more events with that tag.))
• Rework requests to be more like events (Have conditions, and actions to fire on fail and actions to fire on success. Default actions are as now, favour changes.).
• Rework invasions to be more like events (Have conditions, and actions to fire on: Initial warning, reminder, invasion started, victory over invasion, defeated by invasion.).
• Add custom campaigns.
• Add ability on custom messages to mute the sound or background music that is attached.
• Add ability on custom messages to display external images.
• Allow multiple languages for custom messages to be supported for a scenario / map. Load ad hoc of files.
• Add event grouping. Maybe group by tag? (Low priority. We do have export/import to/from XML.)
• Add search functionality in events UI. (Low priority. We do have export/import to/from XML.)
• Allow debug mode to import and replace custom messages.
• Allow debug mode to import and replace custom variables.
• Add exporting of custom empire maps to XML.
• Allow conditions to be inverted.
• Add duplicate button for events. Makes new event with same actions and conditions.

Proposed triggers:

• On new game year.
• On building deleted (should in memory keep the cause, ie. fire, collapse, user delete, war, etc. Should also keep list of all buildings, in case of multiple in a single tick (area delete))
• On user action such as 'changes taxes', 'send off troops', etc.)

Proposed conditions to add:

• Custom variable logic check. ~ variable uid + value + check (==, <=, >=, < or >)
• Number of buildings in an area. ~ Building type + value + check (==, <=, >=, < or >) + grid_offset + radius.
• Number of units in an area. ~ Unit type + value + check (==, <=, >=, < or >) + grid_offset + radius.
• Total stored resource check. ~ Resource type + value + check (==, <=, >=, < or >)
• Free storage for resource check (respects config). ~ Resource type + value + check (==, <=, >=, < or >)
• Percentage of pop class ~ Class + value + check (==, <=, >=, < or >).

Proposed actions to add:

• Change custom variable value. ~ Variable uid + value + type (set or add).
• Enable all events with tag ~ Tag + months before events become active.
• Disable all events with tag ~ Tag.
• Destroy all buildings in area ~ Grid_offset + radius. (Refer to building_destroy_by_collapse)
• Destroy all native buildings in area ~ Grid_offset + radius.
• Convert area to clear land ~ Grid_offset + radius. (Refer to add_terrain)
• Convert area to water ~ Grid_offset + radius.
• Convert area to rocks ~ Grid_offset + radius.
• Convert area to forest ~ Grid_offset + radius.
• Add fertile land to area ~ Grid_offset + radius.
• Stop building production for time. ~ Building category (All farms, all workshops, specific type) + type (if category is type) + time (months duration that production is paused).
• Adjust god mood ~ Target god (All, Venus, Mars, etc.) + value
• Trigger god blessing ~ Target god
• Trigger god curse ~ Target god
• Win scenario. ~ No parameters.
• Lose scenario. ~ No parameters.
• Remove resource from storage. ~ Resource type + amount to remove (cannot add.)
• Add resource to storage. ~ Resource type + amount to add (cannot remove).
• Actions to enable and disable gifts to Caesar.

Bugs to fix:

• Noticed a small bug with the UI when i hover over - in the set money it highlight accept button as well (Marek)
• Building count does not work on highways. (Also check roads and walls and gardens and such.)
• When exporting custom events. It does not update internal ID references for things that use tag references to custom messages or custom empire elements (cities) in the XML. Resulting in invalid export. When changing custom empire, custom variable or custom message, update the internal reference IDs for that element in memory.