updated todo list
created discontinuous1D
updated todo list
removed two tests that seem redundant ?
modify input of all 1D test cases to match new format

everything that is related to the particular code is inside the field
model{i}.name_of_code
add a method that retrieves new points on the boundary of the domain
updated todo list
integrated the method MergeMeshes and XR2XI into the mesh class
cleaned the file from beam details
cleaning beam improvements
passing the method MergeMeshes into the mesh classes
debugging the compatibility of the new classes for 1D problems