[crossfire] Reimplementing seasonal weather.

[Andrew Fuchs]

I just had a conversation on IRC with Raphaël Quinet, relating to
seasonal changes to the world. I was thinking about making an ice
dungeon in the middle of a lake, that, by using the existing scripts
relating to time, would only 'exist' during winter when the lake freezes
over.
Raphaël brought up the point, that if such a dungeon existed, it would
make sense to have most of the world change to visually indicate the
current season to players. Think about trees loosing their leaves, snow
appearing on the ground, and lakes freezing over.

A few ways for this to be implemented came up:
  * Allow the scripts that replace objects based on time to be attached
to regions. However, this could affect indoor maps unless they are
excluded by the code.
  * Create (or modify) archetypes that would change, based on the
season. This could be done with C code or by attaching scripts.
  * Have attributes that specify how such objects change.

A few things should be considered if this is done:
  * It would also be nice to allow various 'climates' to be specified by
region.
  * Regardless of the implementation, special care should probably be
taken to preserve special attributes of the objects being replaced or
modified. If this is not done, exits and other objects can break.
  * If lakes and rivers are to freeze over, attention should be paid to
areas where water is used to block players (such as the lake south of
Brest). However, if we solve these issues, it also allows us to give
pilot-able boats to players. Possible solutions include, not freezing
certain parts of lakes, or the creation blocking tiles such as slush or
very thin ice.
-- 
Andrew Fuchs <fuchs.andy AT gmail.com>