Fixes GH-777.

Fixes GH-778.

Fixes GH-589.

Specifically, making sure that they start with "exa", which is something that's been bugging me recently.

Fixes GH-839.

Fixes GH-202.

It inadvertently contained the machine build time, which meant it stopped working once the Vagrant machine was rebuild.

Fix deducing git ignored state for files too, not only directories

Fix --git deducing ignored state in unintuitive way

Fix month name not following locale when date is in current year

Fix `EXA_GRID_ROWS` not working in some cases 

It makes sense to consider that a directory has the aggregated status of all the files under it.

The exception is that for the ignored status, it’s more useful and intuitive to consider that it applies to everything under it.

- A directory containing an ignored file is no longer considered ignored
- A file inside an ignored directory is now considered ignored

Use thousand separators again and fix alignement when it’s not ASCII

• Bring what's shown in the version string in line with my other projects (URL, description, git hash and date for release-mode non-final builds only, potential for colours in the future)
• Show +git or -git depending on feature status
• Tests for the above, and for checking that the command-line flag is warned about

Fix completions.zsh syntax

documentation: add hint how to install exa on Android / Termux

This also cleans up the release profile in Cargo.toml, which was having its default settings overridden with identical default settings.

• The spaces between icons and filenames are now coloured too
• Some icons are different
• File sizes are now more accurate
• New help text, which needed a newline at the end