Added mergeLog mutation.

graph2/schema/root.gql

@@ -120,6 +120,9 @@ type Mutation {
   # Split a log
   splitLog(input: LogSplitInput!): Log!
 
+  # Merge a log
+  mergeLog(input: LogMergeInput!): Log!
+
   # Edit a log
   editLog(input: LogEditInput!): Log!
 

graph2/schema/types/Log.gql

@@ -129,10 +129,24 @@ input LogSplitInput {
   "Log ID"
   logId: String!
 
-  "After Post ID"
+  "Split out all posts from and including the post with this ID"
   startPostId: String!
 }
 
+"""
+Input for mergeLog mutation.
+"""
+input LogMergeInput {
+  "Target log ID"
+  targetLogId: String!
+
+  "Source log ID"
+  sourceLogId: String!
+
+  "Remove the source log after merging"
+  removeAfter: Boolean
+}
+
 enum LogImporter {
   """
   mIRC-like: This importer parses logs that copied from mIRC posts without spaces.