fix: don't remove groups by name as multiple can coexist (#15)

Author: rigor789

lib/pbxProject.js

@@ -542,11 +542,6 @@ pbxProject.prototype.findMainPbxGroup = function () {
 pbxProject.prototype.addPbxGroup = function (filePathsArray, name, path, sourceTree, opt) {
     opt = opt || {};
     var srcRootPath = $path.dirname($path.dirname(this.filepath));
-    var oldGroup = this.pbxGroupByName(name);
-    if (oldGroup) {
-        this.removePbxGroup(name, path);
-    }
-
     var groups = this.hash.project.objects['PBXGroup'],
         pbxGroupUuid = opt.uuid || this.generateUuid(),
         commentKey = f("%s_comment", pbxGroupUuid),