Rewrite cross-platform symlink logic

[HenningCash]

180 broke symlink creation on windows so i decided to rewrite the part completly.

• As mentioned somewhere in the PR let's use symlink() for both windows and unix so no need for escaping, etc
• The _symlink() method was missing a return statement for symlink creation state so we can also drop the redundant check afterwards with readlink().

[Flyingmana]

thank you very much