Clarifies sort-by-date code
Adds .cmd launcher to run the PowerShell script
Fixes corner-cases where user wants to download 0 of a given podcast (does
not want to download anything) or there is only 1 podcast to be
downloaded
Improves "Yes"/"No" handling
- "Yes"/"No" values are now always a string (previously they were booleans
  if instantiated instead of being read from CSV)
- isYes and isNo routines check for the strings "y", "yes", or "true"
Adds feed caching
Adds gitignore rules
Adds .gitattributes
Normalizes line endings