Boost.Geometry 0.8.0 index source code added to Sandbox Branch

[SVN r68753]
types changed in rtree, filters added, translators added

[SVN r68755]
tests added

[SVN r68756]
translators used, interface changed

[SVN r68980]
index translator example added

[SVN r68981]
filters now uses new interface

[SVN r68987]
leaves now stores values only

[SVN r69051]
tests redesigned

[SVN r69087]
tests redesigned

[SVN r69090]
execution time tests added

[SVN r69111]