added set_time_limit()

closes #1
list of tables is now taken from `information_schema` database to make sure only real tables are used

closes #2
after convertion make change the default charset and collation
this is an optional step on non-empty and textual tables, but required for the rest

closes #3
closes #5
removed unnecessary equal signs in ALTER DATABASE query
Merge branch 'develop' into release/0.2