incorrect output for skinvessel example

[ShijieYan]

[fangq]

@ShijieYan, the bug should be now fixed. Instead of removing the scaling code in mcx_preprocess(), I removed the pre-scaling in mcx_loadconfig and mcx_loadjson in dcdb117.

mcx_preprocess() is now the unified preprocessing function shared among mcxcl/mcxlabcl/pmcxcl to remove duplicated preprocessing codes.

I have just retagged the v2023 release, rebuilt all binaries (only mcxcl/MCXStudio packages affected, but I updated mcxlabcl and pmcxcl regardless).