Current file handling of ROME is based on run number. This way is simple and easy to understand. But 
there are some arguments on it.

(i) In case of .mid file. ROME assume the file name is like run00001.mid. But this is not always true. 
MIDAS users can have different name.

(ii) ROME saves one TTree in one file. But there are cases that user want to save several TTrees in a file

(iii) Especially rare event search experiments like MEG, one file may contain signal candidate events 
from several runs.

To solve this issue one idea is to move from run base I/O to filename base I/O.

* Input
Users may specify filename instead of run number with command line option like.
XXXanalyzer.exe -f run00001.mid,run00002.mid

Then ROMEAnalyzer provides information of filename to DAQ class.

How files are handled is depending on DAQ class. Normally each files will be read one by one.
But in case of bartender program, they will be read in parallel to mix.

In case of .mid file, run number is written in run header of files.
ROMEMidas should change current run number at the BeginOfRun.

* Output
For the output filename we can employ same technique as database path.
This way users can use also run number and some other parameters.
And they can store several TTrees in a file.

  <Tree>
      <TreeName>tree</TreeName>
      <TreeOutputFileName>"%s#.root",gAnalyzer->GetGSP()->GetFilePrefix()<TreeOutputFileName>
      <Branch>
        <BranchName>kine</BranchName>
        <RelatedFolder>Kinematics</RelatedFolder>
      </Branch>
  </Tree>
 

This change is quite big, and it affects all ROME users.
We have to discuss enough on it before changing.

(One choice is to remain run number base I/O.)