AP_Baro: rename AP_Baro_BMP085_HIL to AP_Baro_HIL

there is nothing specific to the BMP085 in it
libraries: fixes for AP_Baro_HIL
Copter: fixes for AP_Baro_HIL
Plane: fixes for AP_Baro_HIL
VARTest: fix for AP_Baro_HIL
AP_Baro: removed HIL constructor

this wasn't calling the parent class
AP_Baro: cleaned up setHIL method

move pressure calculation into library
Copter: simplify setHIL for baro
Plane: simplify setHIL for baro
AP_ADC: removed unused setHIL method
SITL: use new baro setHIL method