The gdal/swig/python/samples/ogr_layer_algebra.py should be promoted to an official Python script

Steps:

• move it to gdal/swig/python/scripts
• create a new test script for it in autotest/pyscripts/test_ogr_layer_algebra.py
• write a documentation page in doc/source/programs/ogr_layer_algebra (and link it to the index)

The main constructor from existing CSR/CSC data is e.g. try_from_csr_data. However, this deliberately rejects unsorted input. However, if the only issue with the data is that the column indices are not sorted, then this is fixable. We should provide a similarly named `try_from_unsorted_csr_d

When I edit a polygon with a zoom level low and I snap this polygon to another one, it's very common the created snap point is not exactly on the line / point.
For me, it's a problem regarding I control if these polygons are not intersecting.

Synfig version & platform:
Building from source
Fedora Linux

Issue description:
Use the advanced project-wise search feature from your preferred IDE and track down the keyword DockManager with case sensitivity turned off.
There are multiple files that included that class's header file but are not using it.

Here's how it looks like on Qt Creator:
![Screenshot_2021-06-10_16-43-3

Add Runnable links of the code below the example.
Use link name Run Code which links to a Online C++ complier conatining the example code.
Use Rextester as the Online C++ Compiler (If you have a better suggesstion please comment).

Follow below steps to generate the Run Code Link.

1. Go to Rextester
2. Copy or write the example

An option like $ fio cat --bounds w s e n --bounds-crs <crs> --dst-crs <crs> would allow for filtering prior to reprojection, like $ ogr2ogr -spat w s e n -spat_srs <crs>.

See Toblerity/Fiona#210 for a discussion about standardizing bounding boxes as --bounds w s e n rather than --bbox w,s,e,n.