usermanual: improve look when in html or wordpress format

* this fix only improves the look if java, saxon and docbook's saxon extensions can be found
* be prepared for a looong processing time: saxon runs really slow!
* we ignore warning "Cannot find CatalogManager.properties" for the time being
usermanual: setting up OpenCL on AMD/ATI devices
usermanual: docs on new dithering parameter for module vignetting
usermanual: revamp build scripts with better detection for saxon and xsltproc

also mention saxon as recommended XSLT processor in README file
Usermanual:
 Fix Saxon detection for Ubuntu docbook-xsl-saxon
usermanual: fix xsltproc fallback in case saxon docbook extension library is not found
fix cmake warning in FindSaxon.cmake
Olympus XZ-1 wb_presets update stolen from UFRaw
Guard old version of Exiv2 against the Samsung2 MakerNote cleanup