The ornamental design for a projector, as shown and described.
FIG. 1 is a front perspective view of a projector;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is an enlarged front view thereof;
FIG. 4 is an enlarged rear view thereof;
FIG. 5 is an enlarged left-side view thereof;
FIG. 6 is an enlarged right-side view thereof; and,
FIG. 7 is an enlarged top view thereof.
The broken line showing portions of a projector is included for the purpose of illustrating environmental structure and forms no part of the claimed design.