* Remove `match_string()`, `match_number()`, and `match_word()`
* Remove `match_word_with_extrasymb()` and `match_word_til_equal_mark()`
* Adapt unit test for `match_number()` to `match_number2()`
* Adapt unit test for `match_string()` to `match_string2()`
Note: the unit tests were testing for the old version of the functions, and
the interfaces for these functions changed slightly, so I had to also edit
the tests.
As of writing, this PR has no merge conflicts with #8211
Additional changes during review:
* Explicitly set up is_[float/signed]_val to be changed before each call
* Structify the tests and fix uninitialized variables
