Added STRtree to optimize the transect creation
* using line growing algorithm to guess length of transects (infinite line intersected wrong shore)
* build single STRtree for shorelines
* query for intersecting geometries
* calculate intersection points
* use longest intersection point
Merge branch 'master' of github.com:USGS-CIDA/coastal-hazards.git
A couple quick fixes
* Using 1km as transect guess length (grows)
* Add 5m to end of line so it for sure intersects
Merge pull request #72 from jiwalker-usgs/master

Improved transect generation