improve ElementPositionWriter and SDDSColumn

The current implementation of the computation of the data for the ElementPositionWriter and fix a problem with the existing implementation: currently the rows are written as if all elements in a "sector" start and and simultaneously, see the following example

      0.11569476         0     0     0     0     0     0     0     0     1     1 "WEDGE1, MDEGD1"
      0.11931035         0     0     0     0     0     0     0     0     1     1 "WEDGE1, MDEGD1"
      0.11931035         0     0     0     0     0     0     0     0     1     1 ""
      0.11931035         0     0     0     0     0     0     0     0     1     1 ""
      0.11931035         0     0     0     0     0     0     0     0     1     1 "MDEGD1, DEGD1"
      0.12111484         0     0     0     0     0     0     0     0     1     1 "MDEGD1, DEGD1"

The correct output should be

0.115694755         0       0       0       0       0       0       0       0       1       1       "MDEGD1, WEDGE1"
0.1193103499        0       0       0       0       0       0       0       0       1       1       "MDEGD1, WEDGE1"
0.1193103499        0       0       0       0       0       0       0       0       1       0       "MDEGD1"
0.1193103499        0       0       0       0       0       0       0       0       1       0       "MDEGD1"
0.1193103499        0       0       0       0       0       0       0       0       1       1       "MDEGD1, DEGD1"
0.121114842         0       0       0       0       0       0       0       0       1       1       "MDEGD1, DEGD1"

The columns in these two extracts are position, different multipole magnets (dipole to decapole and everything above), solenoids, rfcavities, monitors and others (such as degraders). Ignore the different formatting but notice the second last column (others) in the two rows with "" (first extract from old implementation) which should be 0 instead of 1.

Additionally one can chose a format and precision for each column.