Rewrite #520.
Using `read var?'prompt'` is wrong. It is ksh (and zsh) specific.
Using `read -p 'prompt' var` is also wrong. It is bash specific.
Since we cannot assume which sh is implemented,
we should write POSIX-compliant code.

Co-authored-by: Aisha Tammy <aisha@aisha.cc>

I did edit the line 65 and added directly "mbsync -a" instead of "mailsync...". In current state mutt-wizard doesn't work properly in CLI only environment without X started. This is first step to be able atleast mbsync with terminal only pinentry. The problem still remains in sending an email with terminal only pinentry. Temporary solution for is to activate gpg key before sending an email and send the email before the key times out.

This patch puts the environment variable PREFIX in more use. If
specified, mull-wizard Makefile substitute all instances of prefix with
the provided environment variable.

Signed-off-by: Ayman Bagabas <ayman.bagabas@gmail.com>

I contacted MUTT irc channel to solve severe lags while navigating mailboxes of certain email providers with IMAP) (the emails were not stored locally). After extensive testing, changing the default value of mail_check from 5 to 60 solved my problem. I propose this change because several other people might encounter the same problem (especially yahoo users)