Fixed regression in toggling subpatch gop redrect

* It is supposed to toggle on and off depending on whether the subpatch has scalars only in it. It does this by also intelligently accounting for temporary text objects that are created and need to be filled by the scalar name before they are converted into a scalar class.

* There is one condition the original implementation failed to account for: creating a new text_object in an empty canvas which erroneously still resulted in the assumption that the subpatch consisted of only scalars.

* This patch fixes this special case.

* To test: create an empty subpatch and enable GOP, inside the subpatch create an empty object which will erase GOP until you make that object something concrete (e.g. print). With the patch, the GOP redrect will never dissappear (and it shouldn't).
8 jobs for gop-redrect-n-scalars-regression in 232 minutes and 22 seconds (queued for 57 minutes and 40 seconds)
latest
Status Job ID Name Coverage
  Test
passed #22402
x86_64 stretch debian
debian_stretch_x86_64_deb

00:40:18

passed #22404
dmg v10.11 osx
osx_10.11_x86_64_dmg

00:23:43

passed #22405
dmg v10.8 osx
osx_10.8_x86_64_dmg

00:21:29

failed #22407
stretch arm raspbian
raspbian_stretch_armv7l_deb

passed #22403
x86_64 v16.04 ubuntu
ubuntu_16.04_x86_64_deb

00:35:00

passed #22422
i386 windows
windows_i386_innosetup

01:51:51

passed #22421
windows i386
windows_i386_innosetup

02:05:44

failed #22406
i386 windows
windows_i386_innosetup

00:00:48

 
Name Stage Failure
failed
raspbian_stretch_armv7l_deb Test There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log