Added Microsoft.Win32 namespace to FormMain.cs.
Added license and readme files to the solution.
Changed screenshot URL to use GitHub project page.
Changed the download link to use the project page.

GitHub deprecated the downloads feature in December of 2012.
Changed DragEnter event to only accept file drops.

Without this check it is possible to drop all kinds of random things
(like text) on the form, which would then cause an error when trying to
get file information about the object. Related to pull request #2.
Changed FileStream to use read only access.
Changed MessageBoxIcon.Exclamation to Warning.

Just for the sake of consistency. They both use the exact same icon.
Change MessageBox captions to use form Text property.
Added program icon.
Renamed maxFileSize to MAX_FILE_SIZE.
Moved file name render to the bottom of ProcessFile().
Moved RegistryKey to using block in GetMimeType().

It turns out that the RegistryKey class implements IDisposable.
Cleaned up GetMimeType() registry code.

Minor refactor to not make two GetValue() calls for no reason.
Added no file extension check to GetMimeType().

Because there's no reason to even look at the registry if the file does
not have an extension.
Noted media type output is best effort in readme.