Fix project generator build on linux

The path to the projectGeneratorSettings.xml was wrong
Merge pull request #1818 from rogerzanoni/linuxbuild

Fix project generator build on linux
Revert "Fix project generator build on linux".

This reverts commit 8f12ae44e9973c9a1a19f5f9c2e63c0cc60b7d1f.
It was erroneously merged into master, the error was already fixed in develop.
as discussed in issue #1704 the ofxThreadedImageLoader was a hungry thread that did not even sleep.  This has been changed into an intelligent wait/notify thread scenario.
changes per pull discussion.  Only one lock, of standard naming convention, switched order of lock/signal
removed 2 unecessary unlocks
Revert "removed 2 unecessary unlocks"

This reverts commit ea6895e9341a3ebe390f374010b2602447f6764f.
removed unecessary unlock, added lock around images_async_loading structure
make try/catch smaller
lock on images_to_update
Merge branch 'ofxThreadedImageLoader-issue-1704' of https://github.com/labatrockwell/openFrameworks into bugfix-threadedImageLoader
several fixes for ofxThreadedImageLoader + ofURLFileLoader