Expanded tabs to spaces using the commands below.

This expands tabs to 4 spaces in CMakeLists.txt, cpp, c, and h files.
All tabs are replaced, even in quotes, and ones not at the start of a line.

```bash
find . -name 'CMakeLists.txt' ! -type d -exec bash -c 'expand --tabs 4 "$0" > /tmp/e && mv /tmp/e "$0"' {} \;
find . -name '*.cpp' ! -type d -exec bash -c 'expand --tabs 4 "$0" > /tmp/e && mv /tmp/e "$0"' {} \;
find . -name '*.c' ! -type d -exec bash -c 'expand --tabs 4 "$0" > /tmp/e && mv /tmp/e "$0"' {} \;
find . -name '*.h' ! -type d -exec bash -c 'expand --tabs 4 "$0" > /tmp/e && mv /tmp/e "$0"' {} \;
```

Use this link to view the diff with whitespace changes removed: https://github.com/opensim-org/opensim-core/pull/157/files?w=1