Smart update of generated .coafile

There is a possibility that the information extracted from a configuration file changes after the configuration file is modified by the user.

The modifications can be detected by comparing the file’s last modification time and quickstart's last run time. If the file is modified, the corresponding information can be automatically extracted again and reflected in the .coafile generated by coala-quickstart.

difficulty/medium

status/needs design

Start by tracing how coala-quickstart records its last run, reads the configuration file, extracts information, and generates the .coafile. Decide how modification times should be compared and when extraction should be repeated. Done means a changed configuration file is detected and the corresponding information is refreshed in the generated .coafile.

Written by the indexing model from the issue text.