Boolean logic relations allowed:
  AND, OR, NOT (!)

Relational expressions allowd:
  =, !=, >, >=, <, <=


General idea
------------

All expressions will have at least one relational expression.  Each
relational expression assume the lefthand side is a variable name, and
the righthand side is a literal.

 DEPLOY_STATE = TRUE
 !(DEPLOY_STATE != TRUE)
 (DEPLOY_STATE = TRUE) or (DEPLOY_STATE = MAYBE)
 ((QUALITY <= 75) and (K != 9)) or (DEFAULT = no)

Literals - strings or doubles
-----------------------------
Recall that all MOOS variables are either a string or a double
(numerical value). Likewise all literals are either a string or a
double. If the literal is given in quotes, it is treated as a
string. If not in quotes, it will be treated as a double if it 
represents a numerical value, and a string otherwise. 

Examples:

  (STATE = "TRUE")   literal is treated as a string   
  (STATE = TRUE)     literal is treated as a string   
  (STATE = 888)      literal is treated as a double
  (STATE = "888")    literal is treated as a string


Use of parentheses:
-------------------
If boolean conditions are used, parenthesis must surround each
subcomponent:

Examples:

  ((K <= 98) or (RAW != 0))     LEGAL
  (K <= 98) or (RAW != 0)       LEGAL
  K <= 98 or (RAW != 0)         ILLEGAL
  K <= 98 or RAW != 0           ILLEGAL

  (A=1) and (B<2) and (C!=4)    ILLEGAL
  ((A=1) and (B<2)) and (C!=4)  LEGAL