Mini-overhaul pt-deadlock-logger: change --interval default from undef to 30, add --iterations, remove --print, add --quiet, use explicit --columns default, remove --collapse, change default --clear-deadlocks table to percona_schema.clear_deadlocks, refactor the code, use Cxn and Runtime, remove some global vars.

t/pt-deadlock-logger/samples/deadlocks_tbl.sql

@@ -0,0 +1,19 @@
+CREATE TABLE deadlocks (
+   server char(20) NOT NULL,
+   ts datetime NOT NULL,
+   thread int unsigned NOT NULL,
+   txn_id bigint unsigned NOT NULL,
+   txn_time smallint unsigned NOT NULL,
+   user char(16) NOT NULL,
+   hostname char(20) NOT NULL,
+   ip char(15) NOT NULL, -- alternatively, ip int unsigned NOT NULL
+   db char(64) NOT NULL,
+   tbl char(64) NOT NULL,
+   idx char(64) NOT NULL,
+   lock_type char(16) NOT NULL,
+   lock_mode char(1) NOT NULL,
+   wait_hold char(1) NOT NULL,
+   victim tinyint unsigned NOT NULL,
+   query text NOT NULL,
+   PRIMARY KEY  (server,ts,thread)
+) ENGINE=InnoDB;