2.0: Merge pull request #8 from murrty/rewrite

Version 2 comes with a complete code redo, because i was bored and youtube-dl-gui was pretty laughable up to now.

My main goal is to make this as accessible to as many people as possible; this means that some power-user options aren't available... exception for custom arguments, which allow you to completely set what you want up.

+added better verification
+updated error logging process
+updated settings
+converter fully works
+static youtube-dl & ffmpeg
+better converter process
+more options for converting files, check the settings.
~audio still has a single setting, sorry.
+Summaries in code (for anyone interested)

+ A compatible version of youtube-dl-gui for people who are on, at least, .NET Framework 3.5. This should ensure that it works pre-Windows 7.

Debug changes:
Fixed the custom extensions being saved and removed the custom extension removal confirmation (frmSettings.cs)
Removed WaitForExit for downloading & converting. Makes bulk downloads/conversions easier. (Download.cs Convert.cs)
Changed "* completed" to "* started" for downloading and converting. (frmMain.cs)
Added a check for v.redd.it to fix any corrupted files that may get downloaded (Download.cs frmSettings.cs Downloads.settings)
Added Force-HTTPS for downloading. (Download.cs)
Hid the debug dates & moved the last debug date to the about form (frmMain.cs frmAbout.cs).