Define Version 5.1 in Makefile

Update 5.0 release date

Version 4.2

Version 4.1

Version 4.0

version 3.0

make sure history signal stays within window bounds

better calculation of split window sizes

avoiding the lost line if LINES is odd
fixing max SNR display on the way

applied 102-kernel26-compat.patch from openwrt

added what sven-la released as horst-1.2, without the directory changes