Kernel < 3.18 requirement reason

[drzraf]

Is your feature request related to a problem? Please describe.

I intended to patch a boot.img of LineageOS 18 build on a Galaxy S4: kernel 3.4

Describe the solution you'd like

1. kptools-linux -f kernel-b should not return a misleading empty kernel image
2. kptools-linux --kpimg kpimg-android should return something more explicit than get_kernel_info(); kernel image magic error
3. The documentation could state why 3.18 is the absolute lower end of the version requirements. What feature forcefully keeps KernelPatch from working on an even older kernel?