Make install.sh more robust to not being root

[plutonium-239]

Instead of just failing if sudo is not granted, the install script now tries to:

1. move ./spf to ~/.local/bin (which is the correct path for user executables according to the XDG Base Directory Spec)
2. Make that directory if it doesn't exist
3. Checks if this dir is in the path, and if not export path to include it (and add to bashrc)
4. improves error messages accordingly.

Here is an example of how it looks with these changes: (ignore the actual colors, my terminal's color profile is different)

One question I had is should I also mention that ~/.local/bin has been added to ~/.bashrc (so that users of other shells i.e. fish/zsh/xonsh etc) would be able to add it to their configs themselves? I am in favour of adding it.
Alternatively, we can try detecting shell and run respective command but not even fzf takes that approach - it asks you to run the right file yourself (out of some provided scripts)

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[yorukot]

thank you for your contribution, this look good to me!

[plutonium-239]

Thanks!
What do you think about the question I wrote about users of shells other than bash?

[yorukot]

I apologize for missing that part of your message. :(

Regarding your question about users of shells other than bash, I believe automating the detection of the user's shell is a great idea. If there's a straightforward way to achieve this in a shell script without requiring additional user input, that would be ideal. The goal of the install script should be to minimize the need for users to manually configure settings or enter additional information.

[plutonium-239]

No worries! :)

I agree, it should be automated. We could use a case statement on the env variable SHELL, which works reliably. I'll push a change with this.