Easy to use, self-contained tileset update script (I-am-Erk#1557)

* try to make tileset update a self-contained no-brainer

* add script to set game directory env var interactively, enable interactive directory in updtset

* add a script to interactively set the tileset

* add option silent to helper scripts, to not pause on error

* fix finding Python script location for file in game directory, minor fixes

* handle more use cases in path helper script

Handle:
* rel. path as argument
* call from or inside game folder
* drag&drop
* interactive

* add script to set LIBVIPS_PATH, minor fixes setting CDDA_PATH

* allow usage of LIBVIPS_PATH in Python files

* minor fix to comments in updtset.cmd

* add docstring to new scripts

* add copy of compose.py, adapt batch script

* add workflow to docs, keep path helper scripts console open on success

doc/README.md

@@ -0,0 +1,3 @@
+# CDDA-Tilesets documentation
+
+The documentation is best viewed in it's [**rendered version**](https://i-am-erk.github.io/CDDA-Tilesets).

doc/SUMMARY.md

@@ -1,6 +1,7 @@
 # Summary
 
 - [Installation & Building](installation.md)
+  - [Windows guide](installation_windows.md)
 - [Style guidelines](style/summary.md)
     - [General](style/general.md)
     - [Items](style/items.md)

doc/installation_windows.md

@@ -0,0 +1,53 @@
+# Windows guide
+
+Guide for Windows users, without touching the Command Line.
+
+## Install requirements
+
+**Python**
+
+Install Python 3 from [python.org](https://www.python.org/downloads/windows/).
+
+During installation, check "Add Python to PATH".
+
+**libvips**
+
+Download the latest libvips distribution from [libvips.github.io](https://libvips.github.io/libvips/install.html)
+(get vips-dev-w64-web-#.#.#.zip NOT vips-dev-w64-all-#.#.#.zip).
+
+Extract the files somewhere.
+
+**Cataclysm-DDA game**
+
+The easiest way to get the game is to use the [CDDA Game Launcher](https://github.com/remyroy/CDDA-Game-Launcher).
+With the launcher, install the latest **experimental** release.
+
+## Setting up paths
+
+For composing tilesets, some path must be known to the respective scripts.
+This section describes the most easy drag & drop approach.
+
+In `CDDA-Tilesets`, go into folder `tools`.
+
+1. Copy `set_game_path.cmd` into the game's folder, and double-click it.
+OR: Drag & drop the game folder onto `set_game_path.cmd`.
+   > Note: This sets the environmental variable `CDDA_PATH`.
+
+2. Copy `set_vips_path.cmd` into the vips folder (e.g. `C:\vips-dev-x.xx`), and double-click it.
+OR: Drag & drop the vips folder onto `set_vips_path.cmd`.
+   > Note: This sets the environmental variable `LIBVIPS_PATH`.
+
+3. Optional: To set a tileset to compose permanently, double-click `set_tileset.cmd` and select the desired tileset.
+If not set permanently, the update script will allow for interactive selection of a tileset.
+   > Note: This sets the environmental variable `CDDA_TILESET`.
+
+After these steps, it might be necessary to restart the computer.
+
+## Compose and update tileset
+
+In `tools`, double-click `updtset.cmd`.
+
+You will be prompted to select a tileset (unless it was set permanently).
+At the first run, `pyvips` will be installed automatically.
+
+If something goes wrong, read the script's output carefully!