Add missing 'artifact.type' to networks

Networks based on commit interaction data now correctly have an edge
attribute called 'artifact.type'.
Value of column 'artifact.type' in commit interaction data is
'CommitInteraction' until potentially overwritten in
artifact network construction

Signed-off-by: Leo Sendelbach <s8lesend@stud.uni-saarland.de>

util-read.R

@@ -863,14 +863,15 @@ create.empty.pasta.list = function() {
 COMMIT.INTERACTION.LIST.COLUMNS = c(
     "func", "commit.hash", "file",
     "base.hash", "base.func", "base.file",
-    "base.author", "interacting.author"
+    "base.author", "interacting.author",
+    "artifact.type"
 )
 
 ## declare the datatype for each column in the constant 'COMMIT.INTERACTION.LIST.COLUMNS'
 COMMIT.INTERACTION.LIST.DATA.TYPES = c(
     "character", "character", "character",
     "character", "character", "character",
-    "character", "character"
+    "character", "character", "character"
 )
 
 COMMIT.INTERACTION.GLOBAL.FILE.FUNCTION.NAME = "GLOBAL"
@@ -952,6 +953,7 @@ read.commit.interactions = function(data.path = NULL) {
         ## Author data will be merged from commit data in \code{update.commit.interactions}.
         interactions["base.author"] = NA_character_
         interactions["interacting.author"] = NA_character_
+        interactions["artifact.type"] = "CommitInteraction"
         return(interactions)
     })))