[lint] Remove unused imports

Left over from various refactoring and rewrites.

discord/ext/commands/bot.py

@@ -33,7 +33,7 @@ import sys
 import traceback
 import re
 
-from .core import GroupMixin, Command, command
+from .core import GroupMixin, Command
 from .view import StringView
 from .context import Context
 from .errors import CommandNotFound, CommandError

discord/ext/commands/context.py

@@ -23,7 +23,6 @@ FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 DEALINGS IN THE SOFTWARE.
 """
 
-import asyncio
 import discord.abc
 import discord.utils
 

discord/ext/commands/converter.py

@@ -25,12 +25,10 @@ DEALINGS IN THE SOFTWARE.
 """
 
 import discord
-import asyncio
 import re
 import inspect
 
 from .errors import BadArgument, NoPrivateMessage
-from .view import StringView
 
 __all__ = [ 'Converter', 'MemberConverter', 'UserConverter',
             'TextChannelConverter', 'InviteConverter', 'RoleConverter',

discord/ext/commands/formatter.py

@@ -26,7 +26,6 @@ DEALINGS IN THE SOFTWARE.
 
 import itertools
 import inspect
-import asyncio
 
 from .core import GroupMixin, Command
 from .errors import CommandError