Add separate SIFT and RANSAC procedures

[arentkievits]

Current:

• Workflow uses render-ws PointMatchClient.java, which works but has limited functionality. The SIFT and RANSAC procedures are combined, giving no insight in the output of SIFT and what goes into RANSAC and limited insight in what comes out.
• Moreover, the PointMatchClient only supports image clipping in stitching with one tile pair at a time, effectively offering no multithread functionality. Currently I've implemented a workaround by using futures, but this calls the client a bunch of times using a single tilepair as input, which is probably not as efficient as with the 3D alignment where we are using the script's own parallelization feature.

Desired:

• Implement SIFT and RANSAC using SciPy routines instead, with correct parameters. This should make the above much easier to do.