SVG export - not working for bitfields

[meggiman]

OS: CentOS
Release: 7.4.1708
Platform: x86_64

The offline editor (v1.9.2-linux-x64) as well as the online editor does not create any file when trying to export a bitfield as *.svg file or *.png file. The live preview works flawlessly but export is not working. For waveforms the export functionality works without any issues.

Steps to reproduce:

1. open editor
2. Type in the following input:

{reg: [
  {bits:8, name: 'REG ADDR', type:6},
  {bits:2, name: 'D', attr: 'Domain', type:2},
  {bits:22, name: 'ACCELERATOR BASE ADDR', type:1}
	],
 config: {lanes:1}}

3. Export with Export SVG... or Export PNG...
4. Observe that no file with the selected name is created.

[drom]

related to #28

[drom]

related to #50
fixed.