Kernel mapping

[jackpot51]

Problem:

The allocator does not map memory correctly, causing allocations to fail when it hits an address that is not identity mapped.

Solution:

Make the allocator remap memory when necessary, refactor the kernel to allow for the use of "logical" addresses

Changes introduced by this pull request:

• Logical offsets for kernel allocations, map virtual memory when allocations happen
• Undo logical offset for use in drivers, when detected
• Do not identity map all memory
• Add three context "zones" for allocating memory to contexts: image, heap, and mmap
• The image zone is for the program's image (text, data, bss, loaded by exec)
• The heap zone is for the program's dynamic allocations (done by brk)
• The mmap zone is for the program's shared memory (while handling scheme operations as a server).
• The mmap zone will also be reused for mapping MMIO

Drawbacks:

This is by no means done in a safe, reliable, consistent, clean, idiomatic, or efficient way, and significant improvements can be made to the code quality and performance.

TODOs:

• Code cleanup
• Improvements for safety
• Improvements for performance
• Testing

Fixes:
Fixes #536
Fixes #549
Fixes #590
Fixes #591
Fixes #592