Fixes to bootloader and linker

[JTEpic]

This PR is meant for those following part 3 of the OS tutorial. It allows correct entrance into the kernel now allowing VGA memory access.

1. Changed the linkerscript align value to 16, 4096 was very high before and would make global variables have incorrect behavior
2. slight syntax/grammer fixes to kernel.h and kernel.asm
3. boot.asm now activates an interrupt clearing the screen/setting the video mode Int 10/AH=00h, also setting the kernel offset since we are loading to 0x100000, and finally copying kernel from 0x10000 to 0x100000. That is more of a temporary fix as we load the kernel to 0x10000 (at the time when the bootloader cant access past 1MB)