`state.tight` might be updated in the rules, so we should set it
after running rules, not before

Replaced with block.listMode (boolean)

Need to zero out blkIndent, failed test:
---
* a
> b
>
* c
---

It should take indent into account:
---
- lev1
- lev2

- next
---

"# foo" should be parsed as "h1", not as a continuation
---
- test
# foo
---

This is now parsed correctly:
---
- test
---

And put blkIndents everywhere appropriate in block rules.

1. For makefiles indentation is <tab>
2. For markdown files whitespace shouldn't be trimmed

This is incomplete yet:

- one element per list only
- list item may contain only one paragraph