d.polar: fix launch module (py3) and write output EPS file

[tmszi]

To Reproduce:

Steps to reproduce the behavior:

1. d.polar map=aspect output=/tmp/polar.eps

Error message:

Traceback (most recent call last):
  File "/usr/lib64/grass79/scripts/d.polar", line 536, in <module>
    main()
  File "/usr/lib64/grass79/scripts/d.polar", line 431, in main
    rawf = file(rawfile, 'w')
NameError: name 'file' is not defined

Expected behavior:

d.polar module should launch normally without error message.

[neteler]

I tested it and it now works when giving an absolute output path.

Yet it fails with a relative path:

d.polar map=aspect output=polar.eps
 100%
Calculating statistics for polar diagram... (be patient)
ERROR: EPS output file path <polar.eps>, doesn't exists. Set new output
       file path.

[neteler]

While at it, would you mind to also fix these two flake8-identified errors?

 ./d.polar/d.polar.py:516:17: E124 closing bracket does not match visual indentation
                ),
                ^
./d.polar/d.polar.py:524:17: E124 closing bracket does not match visual indentation
                ),
                ^
2     E124 closing bracket does not match visual indentation

[tmszi]

I tested it and it now works when giving an absolute output path.

Yet it fails with a relative path:

d.polar map=aspect output=polar.eps
 100%
Calculating statistics for polar diagram... (be patient)
ERROR: EPS output file path <polar.eps>, doesn't exists. Set new output
       file path.

Fixed in the c99de50.

[tmszi]

While at it, would you mind to also fix these two flake8-identified errors?

 ./d.polar/d.polar.py:516:17: E124 closing bracket does not match visual indentation
                ),
                ^
./d.polar/d.polar.py:524:17: E124 closing bracket does not match visual indentation
                ),
                ^
2     E124 closing bracket does not match visual indentation

Yes of course I fixed in the c99de50.