games/dMagnetic: Update to 0.18

• Update WWW and MASTER_SITES as both were switched to HTTPS.

Changelog:

• Fixed issues with graphics
• Fixed some glitches in the textual output

PR: 241885
Submitted by: Thomas Dettbarn <dettus@dettus.net> (maintainer)
MFH: 2019Q4 (bugfix blanket)