Revert "Bumped minimum Boost version to 1.48.0."

This reverts commit 126aec3d3c30327ab5c8e98459d3667cf3b6418d.
This fixes #346.
[GeoLib] Polygon: Make code more readable.
[GeoLib] Test to check if a point is in polygon.
[GeoLib] Activate Polyline test.
[GeoLib] Tests for GeoLib::lineSegmentIntersect().
[GeoLib] Check if two 3d vectors are parallel.
[GeoLib] GeoLib::lineSegmentIntersect(): new impl.
[GeoLib] lineSegmentIntersect: Reuse value.
[GeoLib] Tests for GeoLib::checkParallelism().
[GeoLib] Reworked impl. of GeoLib::checkParallelism().
[GeoLib] Renamed function for better readability.
[GeoLib] Made GeoLib::Point objects const.
[GeoLib] Expanded test for parallel vectors.
[GeoLib] Supplement information to tolerances.
[GeoLib] Rename scpr() -> scalarProduct().
[GeoLib] Make parallel() impl. more readable.

For this reason the reworked class template Vector3 is used.
[GeoLib] New test name reflects the tested functionality.
[MathLib] For readability: Vector::length() -> Vector3::getLength().
[GeoLib] Using Vector3 for better readability.
added two tests to geolib