Fix inconsistent line breaker.

Since most of the code use Windows line breaker, I stick to it.
Fix the empty allowedTags issue.

The problem is that when the allowedTags in the options is an empty list, all
the tags pass the "renderTag" test and can be rendered. This patch should fix
this issue.
Add the missing definition for the 'renderTag' variable.
Fix a logic error which cause tag not rendered.
Merge pull request #1 from yabroad/master

Fix empty allowedTags