x86_64/hex0: Shrink size from 292 -> 229 bytes.
x86/hex0: Shrink size from 182 -> 181 bytes.
x86/hex0: Shrink size from 190 -> 182 bytes.
x86/kaem: Shrink size from 640 -> 632 bytes.
Update comments in POSIX/x86/hex0_x86.hex0
x86/hex0: Shrink code size from 256 -> 190 bytes
Make sure read function works if file descriptor is longer than 1 byte.
Fix minor typos in comments.
Fix UEFI bootstrap binaries.
* Stack must be 16 byte aligned when calling UEFI functions.
* Non-volatile registers have to be restored at the end of each
program.
Sync riscv bootstrap seeds (only comment updates.
Pad stage1 to 512 bytes and rename with img extension.
Add documentation and builder-hex0-x86-stage1 seed.
Refinements from today's discussion
Add a basic C version of hex0
hex0-alternatives: add implementation in POSIX shell
add 'hex0-alternatives' dir for various implementations
Update AMD64 seeds to GAS style defines.
Switch x86 seeds to new GAS style defines.
Also fix exit code from kaem-optional.
Zero some unnecessary fields in PE32 header.
Make hex0 seed for UEFI one byte smaller.