Increment ntokens less eagerly when lexing
Beautify src/lex.c
Use enum constants instead of mojo_toktype_t
Fix token length calculation
Change comment style
Remove redundant empty lines
Remove mojo_open for now
Remove typedefs
Make it obvious that MOJO_TOK_XXX constants start at 0
Define standard error codes
Add "extern" to the mojo_toknames declaration
Rewrite most of src/lex.c
Implement identifier and keyword scanning
Add support for number literals in mojo_lex
Fix a string lexing bug

The character immediately following the opening quote is no
longer incorrectly skipped.
Add the "def" keyword