* **converter.js:** add error if the passed constructor argument is not an object ([d86ed450](http://github.com/showdownjs/showdown/commit/d86ed450))
* **output modifiers:** fix for output modifiers running twice ([dcbdc61e](http://github.com/showdownjs/showdown/commit/dcbdc61e))
#### Features
* **headerLevelStart:** add support for setting the header starting level ([b84ac67d](http://github.com/showdownjs/showdown/commit/b84ac67d), closes [#69](http://github.com/showdownjs/showdown/issues/69))
* **image dimensions:** add support for setting image dimensions within markdown syntax ([af82c2b6](http://github.com/showdownjs/showdown/commit/af82c2b6), closes [#143](http://github.com/showdownjs/showdown/issues/143))
* **noHeaderId:** add option to suppress automatic generation of ids in headers ([7ac893e9](http://github.com/showdownjs/showdown/commit/7ac893e9))
* **showdown.getDefaultOptions:** add method to retrieve default global options keypairs ([2de53a7d](http://github.com/showdownjs/showdown/commit/2de53a7d))
#### Breaking Changes
* Deprecates `showdown.extensions` property. To migrate, extensions should use the new method `showdown.extension(<ext name>, <extension>)` to register.
For more information on the new extension loading mechanism, please check the wiki pages.
- add unique id prefix and suffix to headers ([c367a4b9](http://github.com/showdownjs/showdown/commit/c367a4b9), closes [#81](http://github.com/showdownjs/showdown/issues/81), [#82](http://github.com/showdownjs/showdown/issues/82))
* **options.omitExtraWLInCodeBlocks:** fix for options.omitExtraWLInCodeBlocks only applying in gitHub flavoured code b ([e6f40e19](http://github.com/showdownjs/showdown/commit/e6f40e19))
* **showdown:** fix for options merging into globalOptions ([ddd6011d](http://github.com/showdownjs/showdown/commit/ddd6011d), closes [#153](http://github.com/showdownjs/showdown/issues/153))
The system, however, is not final and will probably be changed until the final version([0fd10cb] (http://github.com/showdownjs/showdown/commit/0fd10cb))
* **allowBlockIndents:** indented inline block elements can now be parsed as markdown ([f6326b84](http://github.com/showdownjs/showdown/commit/f6326b84))
* **omitExtraWLInCodeBlocks:** add option to omit extra newline at the end of codeblocks ([141e3f5](http://github.com/showdownjs/showdown/commit/141e3f5))
* **prefixHeaderId:** add options to prefix header ids to prevent id clash ([141e3f5](http://github.com/showdownjs/showdown/commit/141e3f5))
* **extensions:** showdown extensions were removed from core package and now live in their own repository. See the [project's github page](https://github.com/showdownjs) for available extensions