logic: Added SourceGroupCustomCommand to use with SourcetrailDB binaries

* Added new Source Group type SourceGroupCustomCommand to UI and ProjectSettings
* The Source Group executes a specified command on every source file
* The variables $SOURCE_PATH, $PROJECT_PATH, $DB_PATH, $STORAGE_VERSION can be passed
* The commands are executed after all other source groups finished indexing
* The command is executed with working directory set to project directory
* Errors during command execution are shown as status update and in the Status View
* SourceGroupCustomCommand cannot be partially cleared, when one file needs clearing the project must be fully re-indexed

testing/project_setup/custom_command/1_setup.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+# get absolute path to parent directory of script
+MY_PATH=`dirname "$0"`
+if [[ "${MY_PATH}" != *\\* ]]
+then
+	cd $MY_PATH
+	MY_PATH=`pwd`
+fi
+MY_PATH="${MY_PATH//\\//}"
+
+SRC_PATH=$MY_PATH/data
+WORKING_COPY_PATH=$MY_PATH/working_copy
+
+mkdir -p $WORKING_COPY_PATH
+
+cp -a $SRC_PATH/. $WORKING_COPY_PATH
+
+echo "Setup Complete"

testing/project_setup/custom_command/2_teardown.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# get absolute path to parent directory of script
+MY_PATH=`dirname "$0"`
+if [[ "${MY_PATH}" != *\\* ]]
+then
+	cd $MY_PATH
+	MY_PATH=`pwd`
+fi
+MY_PATH="${MY_PATH//\\//}"
+
+WORKING_COPY_PATH=$MY_PATH/working_copy
+
+rm -rf $WORKING_COPY_PATH
+
+echo "Teardown Complete"

testing/project_setup/custom_command/checklist.txt

@@ -0,0 +1,38 @@
+* Run "1_setup.sh"
+* Start up Sourcetrail
+* Click "New Project"
+* Enter a project name
+* Set "./working_copy" as project location
+* Click "Add Source Group"
+* Select "Custom" -> "Custom Command Source Group"
+* Click "Next"
+* Click "Next"
+* Add "python add.py $PROJECT_PATH $DB_PATH $STORAGE_VERSION $SOURCE_PATH" to "Custom Command"
+* Add "./src" to "Files & Directories to Index"
+* Add "**excl.txt" to "Excluded Files & Directories"
+* Add ".txt" to "Source File Extensions"
+* Click "Next"
+* Click "Create"
+* Validate "All files" is the only option selectable
+* Validate "source files to index" shows "3"
+* Click "Start"
+* Validate Project indexed without error
+* Click "OK"
+* Validate "out.txt" contains 3 lines:
+	<project_path.srctrlprj> <project_db_path.srctrldb_tmp> <storage_version> <source_path>/a.txt
+	<project_path.srctrlprj> <project_db_path.srctrldb_tmp> <storage_version> <source_path>/b.txt
+	<project_path.srctrlprj> <project_db_path.srctrldb_tmp> <storage_version> <source_path>/c.txt
+* Press "Refresh" button
+* Validate "Updated files" is selected
+* Validate "source files to index" shows "3" again
+* Click "Cancel"
+* Click "Edit Project"
+* Change "Custom Command" to "pyt add.py"
+* Click "Next"
+* Validate "Warning appears that $SOURCE_PATH is not defined in command"
+* Change "Custom Command" to "pyt add.py $SOURCE_PATH"
+* Click "Refresh" button
+* Click "Start"
+* Validate "Log View appears showing errors that command execution failed".
+* Close Sourcetrail
+* Run "2_teardown.sh"

testing/project_setup/custom_command/data/add.py

@@ -0,0 +1,6 @@
+import sys
+# import time
+# time.sleep(1)
+
+with open("out.txt", "a") as myfile:
+    myfile.write(sys.argv[1] + ' ' + sys.argv[2] + ' ' + sys.argv[3] + ' ' + sys.argv[4] + '\n')