Add description and dependencies to mod.conf

The legacy `depends.txt` and `description.txt` files are no longer
needed since Minetest 5.0.0 or later will read everything from
`mod.conf`.

This raises the minimum supported Minetest version to 5.0.0.

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 
+### Changed
+
+- The minimum supported Minetest version is now 5.0.0.
+
 ## [1.1.0] - 2019-03-23
 
 ### Changed

depends.txt

@@ -1,2 +0,0 @@
-default
-intllib?

description.txt

@@ -1 +0,0 @@
-Adds various special versions of normal blocks, tools, and other map maintainer tools.

mod.conf

@@ -1 +1,4 @@
 name = maptools
+description = Adds various special versions of normal blocks, tools, and other map maintainer tools.
+depends = default
+optional_depends = intllib