Implement missing function calls and fix shebang detection

[Xevnar]

I created a filetype.detect module that stores the functions used to detect the filetypes of shell files.

The function I implemented checks is the shell name passed to it is in the shebang table and sets filetype to that or it sets the filetype to the shell name directly.

I also moved the analyze_shebang function to filetype_detect since it fits there more than having it in the main module.

I moved getlines to filetype.util and renamed it to getlines_as_string

The shell functions I added were taken from vim.filetype.detect but I modified the behaviour so that it bash, ksh, and dash do not get converted to sh filetype and instead it is up to the user to do so if they want.

I also fixed some broken muttrc lua patterns and added a mapping for .service files.

closes: #79,#34 Can correctly identify shebangs with arguments closes: #63 Can correctly identify python3 files as python closes: #43 Provide an option to set a default filetype closes: #91 all dist#ft functions that are being used have been ported over closes: #73 map .service files to systemd filetype

[Xevnar]

My bad, I didn't know that deleting the original repository also affected the pull request.