The ornamental design for a projector, as shown and described.
FIG. 1 is a perspective view of a projector.
FIG. 2 is a top view of a projector.
FIG. 3 is a bottom view of a projector.
FIG. 4 is a front view of a projector.
FIG. 5 is a rear view of a projector.
FIG. 6 is a left side elevation view of a projector; and,
FIG. 7 is a right side elevation view of a projector.
FIGS. 1, 2 and 6 show various control devices or user interface elements of the projector in broken lines. Additionally, FIG. 5 shows various connectors of the projector in broken lines. The broken lines in the Figures are for illustrative purposes only and form no part of the claimed design.