Fix #73

Move indent related settings from syntax to index.
Fix #126

Signed-off-by: yuexin <yuecn41@gmail.com>

Fix #99.

Reverts #141 which @cirosantilli wrongfully merged.

Add regression tests that would have prevented that.

Correction pointed out by @shanesmith at #147.

Also fix autolinks without angle braces which
were not being highlighted on top level.

1. Fix not only *+- but also \ matched

Need not escape inside [] because backslash codes do not work inside [].
So pattern [\*+-] match also \.

2. Fix not only list but also horizontal are indented

If only space and three '*' or '-' character are in the line,
this line means horizontal item.
If current line is below horizontal item, it need not to indent.
Following example is horizontal item.

---
***
- - -
* * *

And list item must be specified space after [*-+].
Following example is list item.
* foo
- bar
+ baz

But following example is not list item.
*foo
-bar
+baz

Add indent test file for above bugs.

Fix #90

Fix #100.