add TupleMaker

Details:
this class provides an easy way to store a subset of the information
from the SusyNt ntuple to a smaller ntuple
For now only FourMom and event variables are implemented.
The class has been tested in standalone mode, and it compiles within
SusyTest0.
TupleMaker: add option to delay initialization, make close public

Details:
- the initialization of the output file cannot always happen when the
obj is instantiated, because the parameters (file and tree names)
might not be known yet.  Allow for a delayed initialization,
controlled by the user.
- It looks like the TupleMaker d'tor is never called...who knows what
the fuck TSelector is doing...  Just make close() public, and call it
from within Terminate().
too difficult for cint

Details:
cint cannot parse this code; this results in an 'undefined reference
to set4mom blah' when compiling the dictionaries.
Just follow the suggestion on the root pages, and hide this code from
cint (these functions are not needed in the dictionary).
bugfix, set isJet for jets
test TupleWriter within SusySelection
EventParameters::set* methods
TupleMaker::fill: assign events variables
SusySelection: also fill event vars
SusySelection::Process : assign correctly l1; use dummy low-pt leptons
SusySelection : set tuple filename
SusySel : --tuple-out option
submitJobs: add seltuple opt; add template
drawLegendWithDictKeys: marker is opt
plot mt2j from reduced ntuples
diboson color: more visible shade
plot also mljj

Details:
- factorize plotting part, and re-use it when plotting the two
  variables
- compute mljj
- add docstrings
bugfix j1 -> l1
also set met 4-mom
print mt2j to compare with Josephine
utils:subtract_vector