Fix initialization order of fields in MakeStreamLines class

When a C++ object is constructed, the fields (ivars) of that object are
initialized in the order they are declared in the structure regardless
of the order of initializers listed in the constructor. Thus, it is good
C++ convention to list the initializers of the constructor in the same
order they are declared in the class so that there is no confusion about
the order of initialization (which can matter if there are any
dependencies). To help enforce this convention, some compilers warn if
the order does not match. This commit fixes that issue.

This commit also removes trailing whitespace at the end of some lines in
StreamLineUniformGrid.h. My editor does this automatically because
trailing whitespace bugs some programmers.

vtkm/worklet/StreamLineUniformGrid.h

@@ -184,13 +184,13 @@ public:
                     const vtkm::Id nSteps,
                     const vtkm::Id3 dims,
                     FieldPortalConstType fieldArray) :
-                                  timestep(tStep), 
-                                  streammode(sMode), 
-                                  maxsteps(nSteps), 
+                                  field(fieldArray),
                                   vdims(dims),
+                                  maxsteps(nSteps),
+                                  timestep(tStep),
                                   planesize(dims[0] * dims[1]),
                                   rowsize(dims[0]),
-                                  field(fieldArray) 
+                                  streammode(sMode)
     {
     }