* Fix 3103 - add shellcheck shell directive detection.
Searches for shellcheck shell directive to detect dialects for scripts
that do not have shebang.
* Change order of detection of shellcheck dialect
In a situation where the filetype can be wrong (example: something.sh
which is written in bash dialect) and has no hash-bang (since it is
meant to be sourced) then the override specified within the script will
be ignored.
It probably is the most right thing to do if the script author has added
a specific directive; it should trump everything else.
Co-authored-by: Horacio Sanson <horacio@allm.inc>
Co-authored-by: Dino Korah <dino.korah@redmatter.com>
Some files lack a hashbang line but still have an unambiguous filetype.
For example, the file `.zshrc` has the filetype `zsh`.
Augment ale#handlers#sh#GetShellType to fall back to the filetype if
no hashbang line can be found.
