EMI: Fix display of "dock" video

During the run of the "dock" video (first arrival at melee island) only
a black screen was displayed although the sound did work.
The lua code dims (_dimLevel = 1) the scene before showing a video so
that only the video is visible. GfxOpenGL::drawBitmap sets the current
color according to the dim level before it starts drawing the bitmap:

glColor3f(1.0f - _dimLevel, 1.0f - _dimLevel, 1.0f  - _dimLevel);

If there is no other glColor* call before drawing the video, the current
color stays (0, 0, 0) and the video won't be visible.

The bug fix resets the color to (1.0, 1.0, 1.0) after the drawing of the
bitmap at the end of GfxOpenGL::drawBitmap.

engines/grim/gfx_opengl.cpp

@@ -881,6 +881,8 @@ void GfxOpenGL::drawBitmap(const Bitmap *bitmap, int dx, int dy, uint32 layer) {
 			glEnd();
 		}
 
+		glColor3f(1.0f, 1.0f, 1.0f);
+
 		glDisable(GL_BLEND);
 		glDisable(GL_TEXTURE_2D);
 		glDepthMask(GL_TRUE);