Converting file declarations from VHDL'87

To convert file declarations written in VHDL'87 to VHDL'93, replace declarations of the form:

file fd1 : text is in "in_file";
file fd2 : text is out "out_file"

file fd1 : text OPEN READ_MODE is "in_file";
file fd2 : text OPEN WRITE_MODE is "out_file"