Merge the points2binaryimage tool into points2labelimage

[kostrykin]

Previously, the points2labelimage tool did very much the same as points2binaryimage, except that it used different labels. Merging the points2binaryimage tool into the more general points2labelimage tool will reduce redundant code and facilitate future maintenance. This PR also adds the changes from #133 to the points2labelimage tool, and the functionality to use custom labels parsed from the tabular point file.

Another issue with the previous points2labelimage tool was that it required an "original label image" as a mandatory input, but this image was only used to deduce the shape of the output image. Not very user-friendly, this now is not required anymore.

@bgruening Can you please mark the points2binaryimage tool as deprecated and hidden? I have added it to the list #93 that you asked me to create for you a while ago :)

Fix #134

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[bgruening]

@bgruening Can you please mark the points2binaryimage tool as deprecated and hidden? I have added it to the list #93 that you asked me to create for you a while ago :)

Ok, I will work on this asap and notify you here.

[bgruening]

Ok, should be done by tomorrow.