The ornamental design for a projector, as shown and described.
FIG. 1 is a front view of a projector according to the present design;
FIG. 2 is a back view of the projector from FIG. 1;
FIG. 3 is a side view of the projector from FIG. 1;
FIG. 4 is a alternate side view of the projector from FIG. 1;
FIG. 5 is a top view of the projector from FIG. 1; and,
FIG. 6 is a bottom view of the projector from FIG. 1.
The broken lines showing in the figures illustrate portions of the projector that lines form no part of the claimed design. Additionally, the shading lines in the figures show contour and not surface ornamentation.