vtkWeb: Teach launcher.py to wait for ready_line

Rather than just waiting the full timeout check the output of the
process for the ready_line ( which is configured in launcher.json ).
This should resolve timing issues related to server websockets not
being ready to receive client connections. Also in error paths rather
than return status code 200 (ok) return a reasonable error code.

Change-Id: I3cd99ab5758184002500e3b9adc6208d0fd736e0
vtkWeb: Add appropriate error codes for launch requests

Rather than returning 200 ( ok ) set the response code to an
appropriate error code.

Change-Id: I5a474cb0ffd66881216d1600b51a1f560f5b2207
Fixed confusing indentation, no behaviour change

Hopefully it's the indentation that was wrong,
and not that braces were missing... this seems
to be the consensus on vtk-dev.

Warned by clang's experimental -Windent
"warning: statement has higher indent than preceding if, but is not part of it"

Change-Id: I921d4849f1da362e7301ed0cacb2520b3508fd01
Fixed unused variable warning in release

Variable was only used in an assert() and so caused
an unused variable warning in release.

Change-Id: I58e9cba411ae55a3b8a1a28d1b5ddc2d173a6a9d
Merge topic 'vtkCirclePackFrontChainLayoutStrategy-indent' into master

3d1f2d74 Fixed confusing indentation, no behaviour change
Merge topic 'TestPParticleTracers-unused' into master

a46f6116 Fixed unused variable warning in release
Fix center of rotation for WebGL renderer

Change-Id: Id84e31ddca4449a54f869b53dfff374281d3f7ca
Merge topic 'vtkweb-webgl-center-of-rotation' into master

8241ef56 Fix center of rotation for WebGL renderer
Fix WebGL background orientation

Change-Id: I39dc2632178b3faa9cb5d7d2cb5ba4c3451d6c93
Merge topic 'vtkweb-webgl-center-of-rotation' into master

6ec408f0 Fix WebGL background orientation
Merge topic 'vtkweb-launcher-ready-fix' into master

1d12532f vtkWeb: Add appropriate error codes for launch requests
9d81e15c vtkWeb: Teach launcher.py to wait for ready_line
Copy simple TIFF images into buffers more directly

If we have simple, single component, tightly-packed images then
copy them directly into the allocated buffer. If we are clipping, use
memcpy to just copy the subset requested. This is primarily aimed at
accelerating the load times for TIFF volumes. Thanks to Robert
Maynard for the suggested simplications in the templated image
function.

Change-Id: I6c3b10a019fc892b1e1bbbce32841e7f946eb995
Merge topic 'tiff-reader-templating' into master

4e060c24 Copy simple TIFF images into buffers more directly