MySQL: Support CHECK constraint

added list of check constraints to mysql table view

added create, alter, drop check constraints (mysql)

chore: use the correct function to sql-escape

fix: feature detection for check constraints (mysql)

fix: get check constraint info (mysql)

correct the capitalization of a section title

to be consistent with the other section titles

added a missing `</thead>`

adminer/include/version.inc.php

@@ -1,2 +1,2 @@
 <?php
-$VERSION = "4.16.1-dev";
+$VERSION = "4.17.0-dev";