Add more options for the image size in the save dialog

[alexkay]

Moved from https://code.google.com/p/spek/issues/detail?id=16 :

Add the following settings to the save dialog for image size:

• Default, with the width dependent on the length of the song and height dependent on the sampling rate
• Window, with the image size depending on the window size
• Option to enter custom resolution
• Option to always use English for the stream info.

[Ryrynz]

Any chance of an update to this program?