Move to a git based fetch/update client

[agnivade]

This gives us benefits already mentioned here - #9 (comment)

Citing them again for easy lookup-

Speed: Incremental changes

We get incremental changes pulled in: a fetch can download as many revisions as required, 1 being what's considered a shallow clone. Alternatively --depth is provided at the git clone (and thus git fetch as well) level to specify the amount of revisions to be fetched for the initial setup.

Note: running git fetch --depth 1 https://github.com/tldr-pages/tldr master:master only downloads 205.17 KiB on a clean git init . repository. Fetching in the last merged change (from tldr-pages/tldr@35b685f to tldr-pages/tldr@093bb6f) means fetching in 2 compressed commits. I've measured using this script and the output is below:

repos/tldr λ ./size.sh 093bb6f..35b685f
3       package.json
total 3

3 mere uncompressed bytes. Now throw in Packfile compression.

Speed: Smart Protocol

If the user setups ssh access, we get the benefits of using the "start" protocol: https://git-scm.com/book/en/v2/Git-Internals-Transfer-Protocols#The-Smart-Protocol

Speed: Compression

The content comes stored in compressed form by default: https://git-scm.com/book/en/v2/Git-Internals-Packfiles

Integrity

Not only content is SHA-1 verified upon transfers (https://git-scm.com/book/en/v2/Git-Internals-Git-Objects) but can be further verified very cheaply at any point in time to ensure consistency.