frm: add xunit tests.  Add read/write numeric test and fix bugs related to column names in struct on roundtrips.
getTmpDir: suppress some output

Signed-off-by: Mark Histed <mhisted@gmail.com>
frm: add test: read/write/alter for XLS and XLSX.  Fix bugs related to reading/writing and extensions.  Add frm_xlsfinfo to use POI to get the XLS/XLSX type of file on disk.

Signed-off-by: Mark Histed <mhisted@gmail.com>
frm: test case for catching and retrying excel locks via model dialog.  Add code to frm_xlswritepoi to handle this.

Signed-off-by: Mark Histed <mhisted@gmail.com>