rio: allow spaces in working directory path (-cd) when creating a new window via wctl

The initial working directory of a new window may be set by a
`-cd directory` option. However, the `-cd directory` option is
not capable of handling paths with spaces when used via wctl.

To enable paths with spaces the function
/sys/src/cmd/rio/wctl.c:/^parsewctl is extended to handle quoted
directory paths.

Before applying the patch the following will fail to open a new
window by writing to /dev/wctl:

<snip>
 % rio -i window
 % mkdir '/tmp/path with space'
 % echo new -cd '''/tmp/path with space''' window -x rc >> /dev/wctl
 % pwd
 /tmp/path with space
<snap>

The following invocation fails as well:

<snip>
 % window -cd '/tmp/path with space'
 % pwd
 /tmp/path with space
<snap>

After applying the patch the above sequences work as expected,
opening a window running rc with the working directory set to
'/tmp/path with space'.

0 files changed, 0 insertions, 0 deletions