tmp directory model compilation

[tjzurlin]

Bug Fix: tmp model does not recompile when .model is edited locally

Summary

When using a local .model file with the loadModel(writeTemp = TRUE), the compiled model in tmp/ does not recompile when the local .model file is edited.

Root Cause Analysis

A file.copy is used to copy the local .model file to the tmp/ directory. The hash key is then created on the copied tmp model. If the local .model file is edited, the hash is not changed in tmp/ and the tmp model is not recompiled.

Todo:

• Handle path normalization consistently across windows and linux
• Use intermediate source_file for hash comparison and model compilation