Before this change, `fish ./test.fish` would fully resolve the
relative paths and symlinks of test.fish, as reported by `status -f`.
However `source` would not. With this change, both cases return relative
paths. `realpath` may be used by scripts to resolve them.
Fixes#2643
While investigating issue #2619 my first thought was that the problem
had something to do with the "is_interactive_session" global variable.
That preliminary conclusion appears to be wrong (i.e., the problem
lies elsewhere). However, that hypothesis caused me to look at function
"fish_parse_opt" and other mentions of "is_interactive_session".
I decided to take the opportunity to simplify and improve the style of
"fish_parse_opt" since I just spent an hour reviewing the code that
references "is_interactive_session". For example, the "has_cmd" variable
isn't really needed. And there is inconsistent whitespace not to mention
confusion about bool's versus int's and zero versus NULL.
This change moves source files into a src/ directory,
and puts object files into an obj/ directory. The Makefile
and xcode project are updated accordingly.
Fixes#1866
