poppler: fix typo
poppler: remove needless "#if"

Because poppler-glib requires cairo support.
Update LGPL 2.1 files

GitHub: fixes #196

Reported by ktdreyer. Thanks!!!
gdk3 rbgdkwindow.c:  suppress deprecation warnings
gdk3 rbgdkdisplay.c: suppress deprecation warnings
gdk3: remove trailing spaces
fix build error

error: ‘mask’ undeclared (first use in this function)
add _DEVICE macro

Because we have to treat GdkDevice* type.
suppress incompatible pointer type warning
gdk3 rbgdkwindow.c: remove trailing spaces
gdk3: fix code style
gdk3: fix style

"Type *variable" is our style not "Type* variable".
clutter: fix a typo
gdk3-gi: add experimental GObjectIntrospection based Ruby/GDK3 bindings
gdk3 rbgdkdevice.c: implement GDK+3 API method
gdk3: add deprecation method warning
Revert "gdk3 rbgdkwindow.c:  suppress deprecation warnings"

This reverts commit eeeccc927147af47458a102af08e5786e0ad27be.
Revert "add _DEVICE macro"

This reverts commit c43cb8b7bbf3dba62bbdd7000b47a3e3a83d0242.
Revert "gdk3 rbgdkdisplay.c: suppress deprecation warnings"

This reverts commit 042436f8121c84f2b1f0c89924da51082480bd32.