Reorganized system calls into: exec, ipc, listen, map, print, and kdebug.
Removed kernel heap for separation of mechanism and policy. Task data structures
are now statically allocated in the kernel's .data section, and page table
structures are now allocated from the userland (through kpage parameter in map system call).
Started implementing Rust support. Currently, there's only a "Hello World"
sample app. I'll add APIs once the C API gets stabilized (hopefully September).