Introduces the Search command for mailboxes.
Arguments passed are treated as one space-
separated string, passed on to mailfs' IMAP
search interface.
R=rsc, david.ducolombier
CC=plan9port.codebot
https://codereview.appspot.com/13238044
Mail services (such as Google Mail) will often have
directories with names that contain spaces. Acme
does not support spaces in window names. So, replace
spaces in mail directory names with the Unicode
character for visible space.
The code is a bit of an over-approximation and
generally non-optimal.
R=rsc, david.ducolombier, 0intro
CC=plan9port.codebot
https://codereview.appspot.com/13010048
