Problems with Internal Enable mode

[MarkRivers]

There are several issues with Internal Enable trigger mode.

• This mode was broken completely starting with R3-4 in June 2022. It was always sending 0 as the TriggerExposure value due to a bug introduced in the driver.
• The TriggerExposure value was only used in Internal Enable mode. This is confusing, since AcquireTime is used for all other modes.
  • I propose to eliminate the TriggerExposure record was eliminated, and use AcquireTime in Internal Enable mode.
  • This breaks backwards compatibility, but since Internal Enable mode has not worked at all for 3.5 years, it is likely to have a small impact.
  • eigerBase.template, the OPI screens, and the Sphinx documentation need to be modified to remove this record.

[MarkRivers]

This issue is fixed in #81