Automatic partial dump support

This release lets you dump the USER partition, or the whole RAW eMMC.

It is only activated if you don't have enough space in your SD card to dump the whole eMMC.

The USER dumping is done in 15 2GB parts.
This way you can use 4GB+ sd cards to dump the whole eMMC.

The procedure is the following:

1. Run hekate-ipl_partial_dumping payload
2. Select "Dump RAW eMMC"
3. When this is finished, press any key and Power off Switch from main menu
4. Move the files from SD card to your PC to free some space
   Don't move the partial.idx file!
5. Unplug and re-plug USB while pressing Vol+
6. Run hekate-ipl_partial_dumping again and press Dump RAW eMMC to continue
7. Join the files with your favorite cmd or app

Notice 1: Users that only have a 4GB SD card, use the hekate-ipl_partial_dumping_1GBparts payload.
Notice 2: If you have an unfinished partial dumping and want to start anew, delete the partial.idx file first.

Warning: When dumping the eMMC, in parts, you should not power on the switch normally and boot to Switch OS before done. Otherwise your finished backup will probably corrupt, because Switch OS writes on your eMMC even if it seems you done nothing.