generalTime update

["Kalantari Babak" <BABAK.KALANTARI@psi.ch>]

Hi Andrew,

I have made some progress on generalTime driver since the last EPICS
meeting. The main improvements/changes are as the following:

1. EventTime has no call to NTP or any other external time servers
anymore. It completely relies on generalTime. An API to generalTime was
made to allow getting the best available time while excluding a specific
time provider. In this way EventTime, for example, can get the best
available time (excluding itself) to run its PLL for locking to global
time.

2. EventTime validation interface was changed to aoRecord. The VAL field
determines the acceptable difference between the EventTime and best
available time (given by generalTime) to allow validating EventTime.

3. generalTime init routine is called at initHookAtBeginning. We had
problems especially when the sysClkRate is set after generalTime is
loaded. Now it can be loaded at any stage during the startup.

4. Use of "epicsTimeStamp" type instead of "timespec", etc. whenever
possible in EventTime driver.
 
5. Created the following link mainly to allow users to download the
latest release of generalTime package and some little description:
http://epics.web.psi.ch/software/generalTime/ 

I have planned to go ahead with the following:
1. Splitting the Event/Current Time registration routines.
2. API to select which card to be used for EventTime driver

Feel free to make comments/suggestions.

Regards,
Babak