cache the keytype to safe an extra smccall for every request.

this code is from smcFanControl
corrected the sensors for the macpro5,1

1. don't show second cpu info on single cpu systems
2. added ampere of the four drive bays
3. corrected the smc key id for the cpu temperature
4. removed redundant cpu package temperature
Merge pull request #252 from denis2342/master
Merge branch 'master' into develop

* master:
  corrected the sensors for the macpro5,1
  cache the keytype to safe an extra smccall for every request.
the MacPro4,1 has the same smc keyset like the MacPro5,1
use the SMC key "FNum" to read the number of keys

so a macpro with only one cpu lists only 5 fans instead of six like
a macpro with two cpus because the keys for all six fans are
always there even if not all are needed.
Merge pull request #253 from denis2342/master
Some minor changes in project
Merge branch 'master' into develop

* master:
  use the SMC key "FNum" to read the number of keys
  the MacPro4,1 has the same smc keyset like the MacPro5,1