Since we only currently support Cortex-M class devices it hasn't been a problem to have cortex-m specific things in the kernel crate. However, our longer terms goals require that the kernel crate be architecture agnositic.

• Remove support/arm.rs from kernel crate (Move some cortex-m specific code to arch/ #962)
• Remove assembly from kernel crate (kernel: remove asm #1029)
• Remove arch specific stack/register handling from process.rs. (Move architecture-dependent syscall code to arch/cortex-m #1113)
  • Template Process across architectures. (Move architecture-dependent syscall code to arch/cortex-m #1113)
    • Remove the static PROCS variable. (Kernel: Move PROCS array to Kernel struct #1111)
• Remove arm register specifics from panic print. (Move architecture-dependent debugging print code to arch/cortex-m #1115)
• Support more generic MPU interface. (New MPU Interface #1159)
• Move SyscallInterface to the Chip trait. (kernel: make user-kernel boundary in Chip #1191)
• Update changelog with new interface(s) after these changes. (Add undocumented changes to the CHANGELOG #1136, Changelog Updates #1194)