extracts ttrss package from ttrss-tool
returns err from applyDotFile

Previously, would just terminate the program.
Now, that's main's job alone.
logs in before running chosenCmd
shifts dotfile fns to end of file
extracts readPassword() from main()
adjusts spacing via go fmt
stops exporting flagSetPrintUsage()
extracts Subscribe as ttrss.Client method
defines pre-defined category and feed IDs