- Improved retry behavior for failed HTTP downloads
- Added an option to set a [custom user-agent string](https://github.com/mikf/gallery-dl/blob/master/docs/configuration.rst#extractoruser-agent)
- Improved retry behavior for failed HTTP requests
- Improved `seiga` by providing better metadata and getting more than the latest 200 images
- Improved `tumblr` by adding support for [all post types](https://github.com/mikf/gallery-dl/blob/master/docs/configuration.rst#extractortumblrposts), scanning for [inline images](https://github.com/mikf/gallery-dl/blob/master/docs/configuration.rst#extractortumblrinline) and following [external links](https://github.com/mikf/gallery-dl/blob/master/docs/configuration.rst#extractortumblrexternal) ([#48](https://github.com/mikf/gallery-dl/issues/48))
- Fixed extraction issues for `hbrowse`, `khinsider` and `senmanga`