Disable KVM, log everything to serial, fix Makefile

Disable KVM, as GDB breakpoints stopped working.
Makefile: two unquoted paths caused issues, now that my ~/Programming/exscapeOS is a symlink to a path with a space in its name.
Bochs: use ./bootable.iso instead of an absolute path
Serial: Add serial_send_byte(c) to putchar(), to allow for easy scrolling in panic messages etc.
Add FPU support! Haven't tested SSE* yet.