Define the IEspTxSummary interface to encapsulate the transaction summary
funcionality found in IEspContext. Provide a simplified yet generalized
interface to manage a collection of key-value pairs, including these
capabilities:

Insert values into the collection for unique keys, in insertion order.

Update values for existing keys in the collection.

Interrogate the size of the collection.

Purge the collection.

Test the existance of a key in the collection.

Interrogate the elapsed time since the collection's creation.

Serialize the collection into a StringBuffer.

Retain the existing IEspContext interface for summary content additions so
existing usage is unaffected. The requirement for unique keys is new, but does
not affect current usage.

Expose IEspContext's encapsulation for content additions in situations when the
context is not and cannot be available. Any function with access to a context
may continue to use the context's existing interface.

Remove IEspContext methods that distort the log or have no effect. These
removals do not impact current usage.

setCreationTime alters subsequent timestamp values. Timing values that are
not relative to the start of request processing have limited to no value.

flushTraceSummary only prepares the summary to be logged. It does not
generate a new log entry.

Signed-off-by: Tim Klemm Tim.Klemm@lexisnexis.com