parse: Add skip_note for parsing notes

parse: Add ParseError and ParseErrorException for error reporting

parse: Ignore whitespace in text, instead join words with spaces ...

This cuts down on complexity as now only the tokenizer deals with
whitespace and makes whitespace no longer a factor in the language.

tests: parse: Add helper insert_random function ...

This is just to help clean up some complicated looking code.

tests: parse: Document draw_token_by_value

tests: syntax: Rename draw_token_location to draw_syntax_location

tests: tokenize: Move syntax tests to new file

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