HTCFile throws TypeError when input is a Path object

Just FYI, something in cluster_resource.py explodes when the HTCFile object is initialized using a Path object from pathlib. For example:

  from pathlib import Path
  from wetb.hawc2.htc_file import HTCFile
  htc_orig = Path(str_to_htc_file)  # e.g., 'C:/Users/rink/test.htc'
  htc_file = HTCFile(htc_orig)

returns

...
 File "C:\Users\rink\AppData\Local\Continuum\miniconda3\envs\junk\lib\site-packages\wetb\utils\cluster_tools\cluster_resource.py", line 45, in unix_path_old
    filename = os.path.realpath(filename.replace("\\", "/")).replace("\\", "/")
TypeError: replace() takes 2 positional arguments but 3 were given

Perhaps we should type-check and verify user passes a string? Otherwise support them passing Path objects, which are not only convenient but also the recommended standard now.