Changed default database system for 'db_ext' authentication from mysql to mysqli (mysql is deprecated from PHP 5.5)

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2773 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7
Improved error reporting when using 'db_ext' authentication

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2774 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7
Added quoting of table and column names when using 'db_ext' authentication

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2775 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7
Tidied up quoting of identifiers

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2776 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7
Fixed bug when using $db_port with mysql

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2777 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7
Removed debugging info when using $db_port with mysqli

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2778 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7
Allowed use of non-standard port numbers when using 'db_ext' authentication

git-svn-id: http://svn.code.sf.net/p/mrbs/code/mrbs/trunk@2779 25f7e783-145e-4f2d-a9f8-dd7182bfe9c7