use guzzel
Start adding the link checker
Add a class to get all marks with unique values
Group by value_found, not marks_id

otherwise, we would never get all the unique values.... which we need
Return an empty array if it fails
add a method to get the human name
implement the checkLinks method
Start adding a links table
Merge remote-tracking branch 'upstream/master' into metric_links
store the URL hash instead of the full URL
Add a record class for the link status table
Set the date created by default
Implement the scan

Check for cached queries in the database before sending requests
Remove an used class
Make the marking process easier to test

By moving it into its own method
add a method to get the metric mark of a page mark
count 301 links as errors
Add a test for the markPage function
add tests for the getPointDeduction method
Allow more configuration

allow configuring:
* guzzel request options
* the chunk size (max number of concurrent requests)