Arbor.js: fix indentation in a couple of functions.
Arbor.js: Gaussian convolution of slabs to compute smooth cable length
and also to smooth the position of skeleton nodes.
WebGLApplication: add option to smooth skeletons with a Gaussian convolution.

It is surprisingly fast and looks great, removing all jitter.

Could be made even faster by caching distance measurements.
WIP
WebGLApplication: refresh skeletons when toggling Gaussian smoothing.
WIP
Merge branch 'master' into morphology-pca

Conflicts:
	django/applications/catmaid/static/libs/catmaid/Arbor.js
Arbor.js: save two ops (one sqrt and one squaring) for every estimation of Gaussian weight,
increasing performance as always: by doing less.
Added field to choose skeleton line width in the 3d viewer
Arbor.js: new function resampleSlabs

Leaves all root/branch/end nodes in place, and resamples the nodes
in the slabs to a desired node interdistance.

The last edge of each slab (prior to reaching a branch node or an end node)
will be equal or shorter than the desired node interdistance.

The resampling is based on a Gaussian convolution.
Arbor.js: resampleSlabs can now cope with very jittery arbors,
and has a simpler _gaussianWeights function that doesn't require
concatenating strings to create object keys.
Arbor.js: fix 2 errors in _resampleSlab

1. could have added last node twice.
2. was not cloning reused Vector3 instances.
Arbor.js: add comment about future work.
Fix error in measurement table: counts of branch and ends was swapped.
WebGLApp: introducing options to resample the skeleton.

Root, branch and end nodes are not altered. Slabs are resampled so that
nodes have a maximum, constant interdistance of "resampling_delta", in nm.

Reduces e.g. a neuron with 1000 nodes to about 50 nodes when resampling
to a delta of 5000 nm.

At extremely large deltas, the arbor is reduced to root, branch and end
nodes, linked by straight lines between them.
Merge remote-tracking branch 'origin/master' into morphology-pca
Merge remote-tracking branch 'origin/linewidth-setting' into morphology-pca

Conflicts:
	django/applications/catmaid/static/webglapp.js
WebGLApp: fix some of the many whitespace inconsistencies.