binvox header fix (#2486)

Hello ! 

Apparently there has been an update to the binvox file header (tested on
binvox version 1.38), now binvox files includes a new header line that
looks like this :

```
# generated by [binvox], https://www.google.com/search?q=binvox, parameters: ...
```

This PR fixes the binvox parser and header to account for the newline.

Author: mikedh

trimesh/exchange/binvox.py

@@ -57,6 +57,7 @@ def parse_binvox_header(fp):
         space = " "
     if not line.startswith(binvox):
         raise OSError("Not a binvox file")
+    fp.readline()
     shape = tuple(int(s) for s in fp.readline().strip().split(space)[1:])
     translate = tuple(float(s) for s in fp.readline().strip().split(space)[1:])
     scale = float(fp.readline().strip().split(space)[1])
@@ -98,6 +99,7 @@ def parse_binvox(fp, writeable=False):
 
 
 _binvox_header = """#binvox 1
+# Generated by trimesh using Patrick Min format ---
 dim {sx} {sy} {sz}
 translate {tx} {ty} {tz}
 scale {scale}