Add new manual data input function

When opening a data file for processeing fails, make the program enter
an interactive mode that lets the user enter the data manually.
Make the counter global.

Program.cs can now read any number of lines of data from FileIO and
process this data correctly. the variable counter was made global and a
public get() method was added to acces it from outside the class.
Move code to different function

The program has two ways of working, one that reads from a file and the
other one that executes when a file error occurs. Started moving data to
separate both parts.
Continue refactoring

Making both modes of the program functional and separate
Make ManualData() accesible to the whole class