Show more info when previewing variables and fix missing variables or…

… wrong values (PatrickF1#71)

1. Use a simplified output of set --show to present scope info of the variable being inspected. set --show also nicely delineates array values with newlines and index numbers to make them more readable.
2. Read the shell variables' info before even executing the search function in order to capture the shell variables exactly as the user would see them on the commandline. This is actually a bug fix. Before, search variables function actually used the variables from a different scope and the values form a different fish session, so local variables were missing or values had the wrong value. This is a big problem if say, the user wanted to inspect a local variable or $status. Now, they will be able to see all the variables exactly as they are at the time of execution.
3. $history is excluded from the variables that can be searched and previewed for technical reasons, but also to encourage usage of the search command history feature.
4. This change is backwards incompatible for users who set their own key binding because __fzf_search_current_dir now takes in two new arguments. To address that, executing __fzf_search_current_dir without any arguments will print a helpful error message to help users update their key bindings.

Don't follow symlinks when finding files

It seems symlinks often point to massive directories that you wouldn't want to be searching in anyway, so it's more trouble than it's worth to follow them. Resolves PatrickF1#66.

make sure to use ls command when previewing dirs

Relates to discussion in #69

Remove execute permission from search git status file

I must have accidentally set the execute permission on that file while testing and never noticed it until now.

Only support installation with Fisher (PatrickF1#59)

Allow multi-selecting when searching for files (PatrickF1#55)

Also remove emphasis on entity type in feature subheaders

Thoroughly document features and improve configuration section (Patri…

…ckF1#48)

Improve feature explanations by creating a new section and describe the features in a methodical and thorough way, each with their own sub-section.
Additionally, improve explanations of configuration and troubleshooting.

Make code more stylistic and idiomatic (PatrickF1#45)

Use test instead of [ ... ], in accordance with documentation and the rest of the code. fish-shell/fish-shell#1850 says the use of the square brackets for test is highly discouraged.
Use 2>/dev/null instead of 2> /dev/null. This is preferred by fish_indent.
Use string escape "$path" instead of echo $path | string escape

Always repaint command line in search_git_status (PatrickF1#40)

Repaint should always be used because something will always be printed. Currently, if search_git_status is ran outside a git repository, the command line is left dirty with an error message and the cursor on a newline because repaint is not called.

Quote $fish_key_bindings to prevent error when it's not set (PatrickF…

…1#39)