Substance parser cannot parse In

[kai-qu]

The following program does not parse and I believe it should:

Set A
Point B
In B A

Running ./Main snap sub/venn_comp_pt.sub sty/venn_comp_simple.sty gives this error:

Main: sub/venn_comp_pt.sub:3:1:
unexpected 'I'
expecting alphanumeric character, end of input, letter, or newline

CallStack (from HasCallStack):
  error, called at ./Substance.hs:341:18 in main:Substance

[wodeni]

Pushed a fix to the issue with In. Turned out to be more complicated then I thought. It was mostly related to the space consumer. I also upgraded Megaparsec to 6.3 for some new functionalities I used in this commit.
Note that I did not run all examples in our repo, so @hypotext let me know if any example failed in unobvious ways.

[wodeni]

Since we still have a couple of branches working on the older version of Megaparsec, please compile Main with the following command, which hides the newer version:

ghc Main -ignore-package megaparsec-6.4.0