Derived type for file connections

[Beliavsky]

I don't think Fortran's use of integer unit numbers for file connections is ideal. This cannot be changed, but I suggest that stdlib have a file derived type to encapsulate the unit number and other properties of a file. It would have attributes found in the OPEN statement and could look like

type, public :: file
   character (len=1000)  :: name
   integer               :: unit
   character (len=100)   :: action
   character (len=100)   :: status
   character (len=100)   :: access
   character (len=100)   :: form
end type file

Users could declare type(file) variables and pass them, instead of unit numbers or file names, to subroutines.

[milancurcic]

See #14

[Beliavsky]

Thanks @milancurcic -- closing this issue so that further discussion occurs there.