fix issue #2 about inverting headings h2 and h3 | change headings in …

[gtonye]

Before:

==a test== was converted into an <h3>a text</h3>
===a test=== was converted into an <h2>a text</h2>

Now:

==a test== is converted into an <h2>a text</h2>
===a test=== is converted into an <h2>a text</h2>