Markdown filter: extra spaces and empty lines added/removed

*Created by: Kuro Kurosaka *

When a .md file is processed by tikal.sh -x to generate a .md.xlf file, and then it is merged without change by tikal.sh -m, the resulting .out.md file is different than the original .md file. They tend to include extra spaces and empty lines.

Two sample files, found in the comment in another issue #686, are attached.

$ ./tikal.sh -x space1.md
$ ./tikal.sh -m space1.md.xlf 
$ diff space1.md space1.out.md
1,8c1,10
< *   **PointCloudType** - type of point cloud loaded into a Revit document. Each PointCloudType maps to a single file or identifier (depending upon the type of Point Cloud Engine which governs it).
< *   **PointCloudInstance** - an instance of a point cloud in a location in the Revit project.
< *   **PointCloudFilter** - a filter determining the volume of interest when extracting points.
< *   **PointCollection** - a collection of points obtained from an instance and a filter.
< *   **PointIterator** - an iterator for the points in a PointCollection.
< *   **CloudPoint** - an individual point cloud point, representing an X, Y, Z location in the coordinates of the cloud, and a color.
< *   **PointCloudOverrides** - and its related settings classes specify graphic overrides that are stored by a view to be applied to a PointCloudInstance element, or a scan within the element.
< ### Point cloud file paths
---
> * **PointCloudType** - type of point cloud loaded into a Revit document. Each PointCloudType maps to a single file or identifier (depending upon the type of Point Cloud Engine which governs it).
> * **PointCloudInstance** - an instance of a point cloud in a location in the Revit project.
> * **PointCloudFilter** - a filter determining the volume of interest when extracting points.
> * **PointCollection** - a collection of points obtained from an instance and a filter.
> * **PointIterator** - an iterator for the points in a PointCollection.
> * **CloudPoint** - an individual point cloud point, representing an X, Y, Z location in the coordinates of the cloud, and a color.
> * **PointCloudOverrides** - and its related settings classes specify graphic overrides that are stored by a view to be applied to a PointCloudInstance element, or a scan within the element.
> 
>    ### Point cloud file paths
>