port bccbccc9bb53cdc7f2e5238345f69fd754507595 from Pd-l2ork: finally fixed control file for both pre and post 15.10 Ubuntu due to libgsl

port b39417b3d4676fb3275aa31be934fe776718504c from Pd-l2ork: experimental improvements to the Linux build to make it compatible with Ubuntu 16.04

*added lyon to default path
(ported manually, left out control file since it was ported in a previous manual port...)

*updated dependencies that reflect rtcmix~ external needs

*forgot to add two files

 *hopefully fixed the remaining conflicts between pd-extended deb and pd-l2ork deb

 *fixed potential package conflict with old pd-extended due to Gem includes. Moved them to /usr/include/pd-l2ork/Gem/ instead of /usr/include/Gem

from pd-l2ork: 640d3c53ad8cd592b1d757b988e27d3ada2b1779

from pd-l2ork: b9cd12d16229acf3a66accc4ad0bdae03d96f19b

from pd-l2ork: a7f382e3d4ffd84c0e7246fdc2d24afca81784f9

 istalls[sic]."
 ee538990d34d4aea0b1757976d8e8dffbeb21a38

0e1938c2d6b3c460fb6eefd027c990fbb36078f9

*further improved naming convention for settings files (default.settings and user.settings), cosmetic improvements to the indexing prompt of the help browser dialog.

*updated file locations and made names more consistent across all folders (everything now uses pd-l2ok instead of pdl2ork). Placed user settings into ~/.pd-l2ork/ folder and renamed to simply settings, placed xapian search database for the browser inside the ~/.pd-l2ork folder.

made shortcuts more flexible in terms of startup (not forcing JACK, which will help on setups that don't want/need JACK backend), as well as providing intelligent menu shortcuts for ALSA and JACK