Fix spelling and grammar issues

[p-e-w]

This PR fixes a bunch of spelling and grammar issues that I found with LanguageTool using a semi-automated process that I will describe in detail below.

I have focused on issues that are obvious mistakes, rather than just poor style or against some convention. As such, this PR does not attempt to correct:

• British/American spelling inconsistencies, of which there are many.
• Violations of Oxford ise/ize word ending conventions.
• Missing commas, particularly in conjunctive clauses.
• Improper punctuation, such as hyphens being used in place of em-dashes.

The workflow described below finds hundreds of these issues, which may or may not be worth resolving as well. Note that I have thus far only looked at documents from the specification root directory, the appendices subdirectory, and the file modules/end_to_end_encryption.rst, as I unfortunately don't have more time to work on this for now.

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Workflow

Spell- and grammar-checking technical documents is challenging because symbols and jargon invariably generate an overwhelming number of false positives. The following setup works quite well for the Spec:

1. Install Pandoc and Java.
2. Download and unpack the standalone "Desktop" version of LanguageTool from here.
3. Add this custom Matrix.org Jargon Dictionary to LanguageTool's bundled Hunspell version. The easiest way to accomplish this is by replacing the contents of org/languagetool/resource/en/hunspell/ignore.txt with the contents of that Gist. This dramatically reduces the number of false positives.
4. For each Spec document, run pandoc -t plain PATH/TO/SPEC/DOCUMENT.rst | java -jar languagetool-commandline.jar -l en-GB -d 'WHITESPACE_RULE,DASH_RULE,EN_QUOTES,MULTIPLICATION_SIGN,WORD_CONTAINS_UNDERSCORE,ENGLISH_WORD_REPEAT_BEGINNING_RULE,COMMA_PARENTHESIS_WHITESPACE,SENTENCE_WHITESPACE,UPPERCASE_SENTENCE_START,PLUS_MINUS,ARROWS,OXFORD_SPELLING_ISE_VERBS,OXFORD_SPELLING_NOUNS,OXFORD_SPELLING_ADJECTIVES,LICENCE_LICENSE_NOUN_SINGULAR,AN_INVITE,UNLIKELY_OPENING_PUNCTUATION,EN_UNPAIRED_BRACKETS,ANYMORE'.

The raised issues are of fairly high quality, with roughly 30-40% of them being actual problems that warrant fixing.

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Signed-off-by: Philipp Emanuel Weidmann pew@worldwidemann.com

[p-e-w]

Do trivial changes like this require a news fragment? I've read CONTRIBUTING.rst but the answer is still not clear to me.

[turt2live]

Thanks for doing this! I'll take care of the changelogs before merging.