Handle errors when evaluating sclang expressions

[chrisbarrett]

Some of the included extensions, such as sclang-doc-mode, pass the code around the cursor to sclang and use reflection to get info such as documentation. Often the expression passed to sclang is syntactically incorrect, and results in an error being printed to the post buffer.

These expressions need to be evaluated in a way that prevents evaluation errors from being thrown. The function that needs to be fixed is in sclang-extensions-utils.

I don't know sclang well enough to fix this, so contributions are needed if this is to be resolved.

[chrisbarrett]

Completing this should resolve #3.

[dathinaios]

Did you ever check the solution here for this (from #7)?