Segment.md

+Segment original implementation. Provides an easy interface to manipulate, save and restore, segment-like values from the database. Works very similar to the `ActiveRecord::Point`, but for a list of 2 values of them (stored as `x1`, `y1`, `x2`, `y2`). [PostgreSQL Docs](https://www.postgresql.org/docs/9.6/datatype-geometric.html#DATATYPE-LSEG)
+
+The biggest difference between this and a [`line`](https://github.com/crashtech/torque-postgresql/wiki/Line) is that its composition is based on two points.
+
+# How it works
+
+### Migration
+
+Just set the type of the column as `segment` when creating a table.
+```ruby
+create_table "Hit" do |t|
+  t.string  "source", null: false
+  t.segment "trajectory"
+end
+```
+
+### Using it
+
+The column is automatically identified and its value turned into what is defined in [`geometry.segment_class`](https://github.com/crashtech/torque-postgresql/wiki/Configuring#geometry.segment_class) or into a `Torque::PostgreSQL::Segment`. 
+
+This original implementation provides a couple of methods:
+```ruby
+hit = Hit.new
+hit.trajectory.x1
+hit.trajectory.y1
+hit.trajectory.x2
+hit.trajectory.y2
+```
+
+The value can be set in some different manners:
+
+```ruby
+hit.trajectory = '3,2,15,10'
+hit.trajectory = '[3,2],[15,10]'
+hit.trajectory = '((3,2),(15,10))'
+hit.trajectory = [3,2,15,10]
+hit.trajectory = [[3,2],[15,10]]
+hit.trajectory = { x1: 3, y1: 2, x2: 15, y2: 10 }
+```
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