Fixes hybrid body creation

Merge branch 'develop' of https://github.com/janelia-flyem/NeuTu into…

… develop

Fixes connection validation dialog

Improved UI for synapse validation

Fixes build error

Fixes 2d object display in hiding mode

Adds view adjustment

Build fix

Keeps zooming scale for 2D view localization

Extends body split timeout

Splitting a large body or supervoxel may result in a timeout error from the DVID server. Using a longer timeout should reduce the error frequency, although there is no guarantee to avoid the error. This commit also improves error handling in splitting to warn users more explicitly.