Move collections into own folder

src/lib/meson.build

@@ -33,10 +33,11 @@ sources += files('Concrete/PairEnumerable.vala')
 sources += files('Concrete/DirEnumerable.vala')
 sources += files('Concrete/ZipperEnumerable.vala')
 sources += files('Concrete/EmptyEnumerable.vala')
-sources += files('Concrete/Sequence.vala')
-sources += files('Concrete/Fifo.vala')
 sources += files('Concrete/Generator.vala')
-sources += files('Concrete/BinaryData.vala')
+
+sources += files('Collections/Sequence.vala')
+sources += files('Collections/Fifo.vala')
+sources += files('Collections/BinaryData.vala')
 
 invercargill = shared_library('invercargill', sources,
     dependencies: dependencies,