tests: Re-order parser tests

tests: Refactor parser token generation to use strategies

tests: Move utility functions to top of test_parse file

tests: Add whitespace variable for lexer tests

tests: Test tokenizer with empty string

tests: Test that conjoined keywords are parsed as symbols

tests: Make sure text and note tokens aren't accidently nested

tests: Exclude reserved words and shebangs from lexer tests

tests: Fuzz whitespace for text and notes

tests: Test location in lexer texts

tests: Add lexer test for shebangs

tests: Add lexer test for symbols

tests: Add lexer test for keywords

tests: Add test for lexing booleans

tests: Test parser note mechanism

tests: Test text parsing with the lexer

tests: Comment test_parser_fuzz

tests: Add regression test for trailing whitespace in text

parse: Read text literal up to beginning of EndText ...

Using the end of the last word before EndText misses any trailing
whitespace, and it's a lost cause trying to figure out the offset
from after EndText given it might be whitespace or an end of life.

Instead use an offset from the start of EndText.

parse: Add code position to word value ...

This will be useful for finding the start of a word.

parse: Add Word class for lexer tokens ...

Instead of passing around a tuple, use a class.
Rename untokenized tokens to 'words' while we're at it.

parse: Fix tracing in lexer next() ...

This makes the line and column numbers accurate and prints
whitespace properly.

parse: Have lexer position be current instead of future ...

When running next(), self.pos and friends would actually be in reference
to the next call to next(), not the current one.

This is confusing, so change it to make sense.

parse: Fix text literals being cut off when placed at end of file

src: Put repo directory in path so it can find the src module ...

This was also broken when moving things to use 'src' as the module name.

Fixes: 06c8537

make: Style fixup

make: Use src as module in zipapp ...

Moving to using 'src' as a module for testing broke this, so fix it.

Fixes: 06c8537

parse: Account for EOF when checking for whitespace ...

When parsing a file that doesn't end with whitespace (like a new line),
the parser would choke on having no symbols left. Fix that.

Fixes: 1519cef

parse: Decode file as UTF-8 ...

I was testing the parser with binary input.
Use Unicode instead and make sure we pass it that.

Add test harness and simple fuzz test