Logging in is the only tightly bound request/response action.
glvc> Hello <name>\n
glvd> HI\n


All the rest are fairly free form. Since the client is mostly just a
pass-through for stuff to gulm.

glvd sends:
 lock <subid> <key> <rstart> <rstop> <state> <flags> <lvb>\n
 action <subid> <key> <action> <lvb>\n
 cancel <subid> <key>\n
 dropexp <nodename> <mask>\n
 GOODBYE\n

glvc send:
 lrpl <subid> <key> <rstart> <rstop> <state> <flags> <error> <lvb>\n
 arpl <subid> <key> <action> <error>\n
 drop <subid> <key> <state>\n
 GOODBYE\n


<subid> is [0-9]
<key> is [a-zA-Z0-9_]
<state> is [0-9]
<action> is [0-9]
<flags> is [0-9]
<nodename> is [a-zA-Z0-9_]
<mask> is [a-zA-Z0-9_]
<lvb> is either 'nolvb' or [a-zA-Z0-9_]
<error> is [0-9]