GammaLib

The current logic of GSkyMap is that if a file exists, and clobber=true, the map is appended as an additional extension of the file. The logic should however be that the map is replaced.

The question is then how to deal with maps that should be appended to an existing file. There are three possibilities:

• append to a file if clobber=false
• add another flag to the list of arguments for appending to a file
• use the write() method

The last option seems to me the most appropriate one.