Syntax: SHields Up|Down or SHields Transfer <energy>
Raise or lower ship shields, or transfer energy between ship and
shield energy reserves. Raising shields consumes 100 units of
ship energy, lowering them or transfering energy is "free".
NOTE: Shield condition is displayed as +n% for shields up, n%
of full strength, or -n%, for shields down, n% of full strength.
Examples:
SH U Raise shields.
SH D Lower shields.
SH T 500 Transfer 500 units of energy TO shields
SH T -500 Transfer 500 units of energy FROM shields
.