- Add is_animated field to Sticker
- Remove send_animated_sticker (use send_sticker instead)
- Default to 512x512 in case size is unknown (instead of 0x0)
- Add mime.types file to contain a good database of type -> ext mappings
from svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types
- Load mime.type at BaseClient creation and add two convenience methods
for guessing mime types from filenames and extensions from mime types,
guess_mime_type and guess_extension
- Make all send_* method as well as download_media use the new mime type
database via guess_mime_type and guess_extension methods
