Use regex to match special flags for printf

Fixes #1310

Fix #949 (failing on @ in function names)

'@' was previously mentioned in 5005dc0f as a
character needed to fix #909, but was not included
in the actual change at that time.

Fix false positive when indexing into array in cond

Fixes #1268

Add instructions to install linux binary

Do not warn on mv -i (fixes #1251)

Allow trailing comma in exclude flag

Do not warn find --help (fixes #1188)

End column

Check popd flags for -n (fixes #1252)