VCD file format scope issue

[ozel]

While GTKWave has no issue with loading litescope's VCD dumps I found several VCD viewer extensions for VScode don't like the files. Most notably the very promising Surfer viewer (as vscode extension as well as standalone).

I found two issues with the scope declaration:

• the scope start tag seems to require a type qualifier like "module"

  litescope/litescope/software/dump/vcd.py

  Line 92 in eb745d7

  r = "$scope dumped_signals $end\n"

• the scope end tag seems to be "upscope" instead of "unscope"

  litescope/litescope/software/dump/vcd.py

  Line 101 in eb745d7

  r += "$unscope "

VCD format is detailed in this leaked IEEE standard, chapter 18:
https://www.eg.bucknell.edu/~csci320/2016-fall/wp-content/uploads/2015/08/verilog-std-1364-2005.pdf

I am more than happy to submit a pull-request, but maybe there are other reasons for the current format?

@jevinskie worked on this before