Remove all trailing spaces

No real changes, just clean up sources by removing trailing spaces from
all the non-generated files.

This should hopefully avoid future commits mixing significant changes
with insignificant whitespace ones.

interface/wx/math.h

@@ -93,7 +93,7 @@ unsigned int wxCTZ(wxUint32 x);
 */
 int wxRound(double x);
 
-/** 
+/**
    Returns true if both double values are identical. This is
    only reliable if both values have been assigned the same
    value.