Detect Ensenso version at PCL configuration

There should be a minimum Ensenso version in PCL config to make sure users don't have an old EnsensoSDK installed.

On Linux platforms there is a CMake and pkgconfig files installed (SDK 1.3.146 and above) but not on Windows.

$ pkg-config --modversion ensenso-nxlib
1.3.167

See https://github.com/PointCloudLibrary/pcl/issues/1200#issuecomment-150162667 for a multi-platform method; but there's no such macro in the EnsensoSDK:

$ grep -i "1.3.167" /opt/ensenso/ -r
/opt/ensenso/pkgconfig/ensenso-nxlib.pc:Version: 1.3.167
/opt/ensenso/pkgconfig/ensenso-nxlibremote.pc:Version: 1.3.167
/opt/ensenso/manual/html/changelog.htm:<td style="vertical-align:top; width:333px; padding:0px;"><p>1.3.167</p>
/opt/ensenso/manual/html/changelog.htm:<td style="vertical-align:top; width:120px; padding:0px;"><p>1.3.167</p>
/opt/ensenso/manual/html/zoom_index.js: "1.3.167 65 8 64",
/opt/ensenso/manual/html/zoom_pageinfo.js:["changelog.htm","About &#62; Changelog","About Changelog Navigation: About Changelog EnsensoSDK Revision 1.3.167 Last edited 21.08.2015 Changelog Version Changes 1.3.167 Fix: NxView: Adde...",""],