(All commit emails since 4.0.1 checked)
This had to be done now, before the 4.1 tree changes to much, to make it easy to propagate bug fixes to the 4.1 tree.
added set_exec_stdout and set_exec_stderr to mysqlmanager to be able
to redirect stdout and stderr
added support for MY_FULL_IO to my_read, so we can tell it to read
a number of bytes in as many chunks as it takes instead of one try
