Markdown output contains unnecessary escape characters

[jonnyandrew]

Problem

Markdown output contains escape characters that reduce the human-readability of plain text messages.

See

• When the RTE is enabled, the plain body contains escaped characters. element-hq/element-x-ios#1629
• Punctuation marks are prefixed with backslashes in message body element-hq/element-x-android#1260

Proposed solution

Escape characters were introduced with the intention of producing 'valid' markdown (see #770 for details). However, in Matrix, the the plain text content of body only needs to be human readable. Markdown can be used for to enhance and embellish but it's not essential (or part of the spec) that the markdown output is valid/machine readable - especially not at the expense of human readability.

The solution would be to remove all escape characters from markdown output.