Please describe the problem:
Fortran is a case-insensitive language; however, variables are not parsed in a  case-insensitive manner in doxygen.

Steps to reproduce:
!Example code
!>
!!    @param d parameter
!<
      subroutine f(d)
      integer :: D
      end subroutine

Actual results:
With all warnings turned on, doxygen generates the following warnings:

Warning: argument `d' of command @param is not found in the argument list of f(integer D)
Warning: The following parameters of f(integer D) are not documented:
  parameter D

However, doxygen still generates useful documentation:
subroutine 	f (d)
Function Documentation
subroutine f (integer D)  	

Parameters:
    	d 	da

Expected results:
doxygen should be able to figure out that d and D are the same variable

Does this happen every time?
Yes

Other information:
Similar problems are generated by the following codes:

!Example code 2
!>
!!    @param D parameter
!<
      subroutine f(d)
      integer :: D
      end subroutine

!Example code 3
!>
!!    @param D parameter
!<
      subroutine f(d)
      integer :: d
      end subroutine