Use relativepath for file inputs so that task inputs are relocatable

[SidB3]

closes #314

[SidB3]

@szpak - A gentle reminder on the PR. Thanks!

[szpak]

Thanks. Relative paths here seem much more sensible. I'm not sure why the Travis checks didn't kick in :-/. I plan to merge it into devel to test it on CI and probably apply some other pending changes before releasing the new version.

[szpak]

It would be good to have some function test, but I'm not sure how TestKit deals with sharing the build cache (across tests and with the regular builds), so let's skip it.

[szpak]

Btw2, those inputs shouldn't be just String, however, in the times I started this plugin other fancy types were not available... I have to find out how much backward incompatible it would be to "enhance" them.

[SidB3]

Hi @szpak how's the testing going with this change? Any tentative timelines for putting out a new release?

[szpak]

@SidB3 There were some issues with the other changes in the plugin, but today I managed to merge it (manually) and released 1.9.0. Thanks for your contribution!

[SidB3]

Thank you!