Convert possible CP-1253 to UTF-8

This file already contained ASCII '?' characters, suggesting a previous
encoding conversion had already lost some characters. (This seems to
have happened before the file was first committed (2012) to this
repository or its predecessors.)

The character in question here is 8-bit F8, which in CP-1252 (or latin1)
would be 'ø'. Maybe that is what it was, but in CP-1253 (iso-8859-7,
Latin/Greek) it is 'ψ', which seems more likely here.

In any case, we are not losing any information by this conversion.

DeviceAdapters/TwoPhoton/TwoPhoton.cpp

@@ -1194,8 +1194,8 @@ void BitFlowCamera::GetCosineWarpLUT(vector<int> &new_pixel, int image_width, in
 
    /*
    Again this code can be replaced by simpler code 
-   The correction factor = ø /sin ø where  ø = pixel number (from the correct center pixel) * ?ø 
-   ?ø = 2?/freq*127. The corretion factor is calculated for each pixel and applied to the pixel
+   The correction factor = ψ /sin ψ where  ψ = pixel number (from the correct center pixel) * ?ψ 
+   ?ψ = 2?/freq*127. The corretion factor is calculated for each pixel and applied to the pixel
    */
 
    /*9 Loop to shift pixels to new image LUT*/