encodings: Added check for non-8bit encodings in src tree.

This commit sanitizes source files for unicode encodings which
cause failures in downstream flows (docgen, python2 module loading,
etc...).

    * Removed explicit encodings from src files
    * Replaced 2 byte character encodings with ascii encodies:
        ± -> +/-
        ° -> deg
        “ -> "
        etc...
    * Added ctest to check src tree files for non-8bit encodings

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/grovescam/grovescam.hpp

@@ -82,7 +82,7 @@ namespace upm {
 
     typedef enum {
       FORMAT_VGA                   = 7, // 640x480
-      FORMAT_CIF                   = 5, // 352×288
+      FORMAT_CIF                   = 5, // 352*288
       FORMAT_OCIF                  = 3  // ??? (maybe they meant QCIF?)
     } PIC_FORMATS_T;