Modernize spec.
    
    - Reflect ghostscript in Fedora >= 18 having dropped pdfopt.
      Resort to PDFOPT=/bin/cp.
    - Apply patches to allow building against boost > 1.50.0 (Add sdcc-3.2.0.diff).
    - BR: /usr/bin/python to work around lyx packaging bug.
    - Fix up broken %changelog entries.