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