Emphasis was not parsed when it followed directly after some block types
(e.g., lists).
The org reader uses a wrapper for the `parseFromString` function to
handle org-specific state. The last position of a character allowed
before emphasis was reset incorrectly in this wrapper. Emphasized text
was not recognized when placed directly behind a block which the reader
parses using `parseFromString`.
Fixes: #4784
The org reader test file had grown large, to the point that editor
performance was negatively affected in some cases. The tests are spread
over multiple submodules, and re-combined into a tasty TestTree in the
main org reader test file.
