fix calculation of avgCharWidth.

It now ignores glyphs with zero width as required by the OS/2 table spec
fix conversion of none ASCII chars
Change build folders in xcode config files

The put the build results in the Xcode DerivedData folders.
ignore some user files
update upstream
Merge branch 'upstream'
improve code layout and indention

This doesn't change the functionality, only remove some possible
ambiguities.
remove check or "illegal" name IDs
improve code layout and indention
Merge branch 'master' of https://github.com/schriftgestalt/afdko