speedrunr 0.2

Added datasets: platforms and regions for easier id resolving.
Added functions:
- get_leaderboards: Get... a leaderboard.
- get_variables_game: Get a game's variables/values.
- add_platforms and add_regions: Use packaged data to resolve these in run tbls.
- add_players: Similiar use, but actually does API calls, but only one per unique player_id.
API changes:
- rename get_variables to get_variable as it only works on a single variable anyway.
Fixes:
- get_categories now does not fail anymore if one or more categories has no rules.
- get_runs should properly handle pagination (i.e. max > 200) now.

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