Grammar cleanup (#875)

This commit:
* fixes inconsistencies (primarily regarding capitalization)
* fixes non-proper nouns that were improperly capitalized
* fixes reminents from not-so-meticulous copy+paste jobs

src/client/websocket/packets/handlers/ChannelCreate.js

@@ -9,7 +9,7 @@ class ChannelCreateHandler extends AbstractHandler {
 }
 
 /**
- * Emitted whenever a Channel is created.
+ * Emitted whenever a channel is created.
  * @event Client#channelCreate
  * @param {Channel} channel The channel that was created
  */

src/client/websocket/packets/handlers/ChannelDelete.js

@@ -12,7 +12,7 @@ class ChannelDeleteHandler extends AbstractHandler {
 }
 
 /**
- * Emitted whenever a Channel is deleted.
+ * Emitted whenever a channel is deleted.
  * @event Client#channelDelete
  * @param {Channel} channel The channel that was deleted
  */

src/client/websocket/packets/handlers/ChannelPinsUpdate.js

@@ -21,7 +21,7 @@ class ChannelPinsUpdate extends AbstractHandler {
 }
 
 /**
- * Emitted whenever the pins of a Channel are updated. Due to the nature of the WebSocket event, not much information
+ * Emitted whenever the pins of a channel are updated. Due to the nature of the WebSocket event, not much information
  * can be provided easily here - you need to manually check the pins yourself.
  * @event Client#channelPinsUpdate
  * @param {Channel} channel The channel that the pins update occured in

src/client/websocket/packets/handlers/GuildDelete.js

@@ -11,7 +11,7 @@ class GuildDeleteHandler extends AbstractHandler {
 }
 
 /**
- * Emitted whenever a Guild is deleted/left.
+ * Emitted whenever a guild is deleted/left.
  * @event Client#guildDelete
  * @param {Guild} guild The guild that was deleted
  */

src/client/websocket/packets/handlers/GuildMembersChunk.js

@@ -20,7 +20,7 @@ class GuildMembersChunkHandler extends AbstractHandler {
 }
 
 /**
- * Emitted whenever a chunk of Guild members is received (all members come from the same guild)
+ * Emitted whenever a chunk of guild members is received (all members come from the same guild)
  * @event Client#guildMembersChunk
  * @param {GuildMember[]} members The members in the chunk
  */

src/client/websocket/packets/handlers/PresenceUpdate.js

@@ -64,7 +64,7 @@ class PresenceUpdateHandler extends AbstractHandler {
  */
 
 /**
- * Emitted whenever a member becomes available in a large Guild
+ * Emitted whenever a member becomes available in a large guild
  * @event Client#guildMemberAvailable
  * @param {GuildMember} member The member that became available
  */