Rename `Lexer` to `BlockLexer` in `lib/parse.js`
Rename `Lexer` to `BlockLexer` in `lib/parse.js`

eush77/remark,wooorm/remark,yukkurisinai/mdast,chcokr/mdast,eush77/remark,ulrikaugustsson/mdast,tanzania82/remarks,yukkurisinai/mdast,ulrikaugustsson/mdast,chcokr/mdast