- fix prefix argument handling for describe-key
- echo prefix keys after "Describe key: " prompt
- move session commands to qe.c, remove them from tqe
- use byte_quote() in do_describe_buffer()
- use b->offset to track insertions in describe-xxx commands
- eb_putc(), eb_puts() and eb_printf() insert at `b->offset` instead of `b->total_size`
- do not use eb_write() in eb_trace_bytes()
- bump VERSION to 5.3.4p