improve usability of the thl tool

[GoogleCodeExporter]

1. To which tool/application/daemon will this feature apply?
thl

2. Describe the feature in general

  * Remove the need of indicating the service name when there is only one service
  * Add an option to list the last N events 
  * add an option to list the fist N events

3. Describe the feature interface

thl list
thl list -last 10 
thl list -first 10

4. Give an idea (if applicable) of a possible implementation

N/A

5. Describe pros and cons of this feature.

5a. Why the world will be a better place with this feature.

Users will type less, and can get faster info

5b. What hardship will the human race have to endure if this feature is
implemented.

Users may faint at the sight of such improvements

6. Notes

Original issue reported on code.google.com by g.maxia on 17 Aug 2011 at 8:10

[GoogleCodeExporter]

It is no longer necessary to specify the service if there is only one 
replication service configured.  Thl infers the name automatically.  

Original comment by robert.h...@continuent.com on 28 Nov 2011 at 6:43

[GoogleCodeExporter]

Original comment by robert.h...@continuent.com on 23 Jan 2012 at 6:49