This patch removes the restriction that both rect_tx and var_tx must be
 turned off when any daala transform is enabled.
For now, all square transforms are done using daala with the rectangular
 transforms done using AV1.

subset1:

master@2017-09-19T20:41:26.136Z -> daala_tx-dst4@2017-09-19T21:06:47.190Z

   PSNR | PSNR Cb | PSNR Cr | PSNR HVS |    SSIM | MS SSIM | CIEDE 2000
-0.0135 | -0.0201 | -0.0049 |  -0.0619 | -0.0144 | -0.0521 |    -0.0264

Change-Id: Icceb3b0c5bcc40d01fd773b20a2a6588179c0ee6