tokenize: Move syntax to its own module

tests: parse: Add draw_token_by_value function

tests: parse: Move syntax tests to tokenize ...

This helps with mutmut.

tests: parse: Remove unused code

parse: Move Syntax to tokenize and replace Token ...

These are basically the same classes so merge them

parse: Don't nest tokens in values ...

Now that we don't need to copy the TokenType we can just copy the value
directly.

tokenize: Remove TokenType enum ...

In practice this wasn't used: The parse code always checks the value AND
the type. So just check the value only.

tests: parse: Test that parse_text fails with extra StartText tokens

tests: parse: Test invalid content

tests: parse: Draw text syntax tokens ...

This requires fixing a bug for comparing values of different types.

parse: tests: Clarify errors and tests

tests: parse: Draw classified tokens for better coverage

tests: parse: Mutate StartText/EndText for testing

tests: parse: Test parse_text fails without StartText or EndText

parse: Add parse_text to parse a text syntax node ...

No error handling tests are added yet.

tests: parse: Move test to make more sense

parse: Rename TokenStream to SyntaxStream

parse: Require the caller to copy the TokenStream list ...

This is more Pythonic I think.

parse: Add TokenStream class ...

This will be used for stateful parsing, with lookahead in future.

parse: Don't strip non-token syntax ...

This bug was picked up by mutmut.

parse: Use syntax for strip_whitespace

tests: parse: Add draw_syntax_random

parse: Add import_tokens to import tokens to syntax

parse: Add Syntax node ...

Currently this just holds a token, but will eventually hold parsed
syntax tree values.

tests: parse: Use classified tokens for better coverage

parse: Rename remove_whitespace to strip_whitespace

parse: Add parse wrapper function

parse: Add remove_whitespace pass

parse: Move to oldparse ...

This is in preparation of writing a new parser.
Once the new parser is ready then this code can be junked.

tests: Add SPDX license headers