Padelpy

- "from_smiles" and "from_mdl" now accept an optional timeout argument
- "from_smiles" and "from_mdl" will now attempt conversion three times before throwing an exception
- this _should_ reduce indeterminate failures caused by PaDEL-Descriptor
- exceptions thrown by PaDEL-Descriptor are now decoded to UTF-8

- If a RuntimeError is encountered, temporary files (.smi, CSV if not saving) are removed

- Added maximum run-time per molecule for "from_smiles" and "from_mdl" functions
- set to 10 seconds per molecule
- does not affect default wrapper maximum run-time, just these functions

- Initial upload of source code and documentation