fpspreadsheet: Rename test_* projects in folder examples/other to demo_*. Remove dependence on laz_fpspreadsheet package for easier testing, use unit directory for compiled files. Add readme.txt for this folder.

git-svn-id: http://svn.code.sf.net/p/lazarus-ccr/svn@3366 8e941d3f-bd1b-0410-a28a-d453659cc2b4