Fix flot logarithmic axes

Used to use natural log, instead of base 10
Add URL to retrieve the traces for an event

Update API man to include event trace and pulseheight fit urls
To get the traces for an event the full ext_timestamp has to be given
Rename _id to _number in API

Variable names referring to stations/clusters/countries by number
now use the _number suffix instead of the _id, which could be
misinterpreted as the id in the databse
Refactoring: rename variabels with _id to _number

Variables referring to station/cluster/country numbers
used to have the suffix _id, this is now changed to _number
This name corresponds to the field name in the database
and removes possible confusion with the database entry id
Also removed unused variable assignments in the histogram jobs