Refactor Library

The launcher code was in a position ripe for sphagetti, so this rewrites it in a more robust way.
In addition to cleaner code, this provides the following changes:
- Removal of obsolete Mojang authentication
- The rebasing of some internal state into a Sled database
- Tweaks which make some internal mechanisms more robust (e.g. profiles which fail to load can be removed)
- Additional tooling integration such as direnv
- Distinct public API to avoid messing with too much internal code
- Unified error handling in the form of `theseus::Error` and `theseus::Result`

theseus/src/config.rs

@@ -0,0 +1,22 @@
+//! Configuration structs
+
+use once_cell::sync::Lazy;
+use std::time;
+
+pub static BINCODE_CONFIG: Lazy<bincode::config::Configuration> =
+    Lazy::new(|| {
+        bincode::config::standard()
+            .with_little_endian()
+            .with_no_limit()
+    });
+
+pub static REQWEST_CLIENT: Lazy<reqwest::Client> = Lazy::new(|| {
+    reqwest::Client::builder()
+        .tcp_keepalive(Some(time::Duration::from_secs(10)))
+        .build()
+        .unwrap()
+});
+
+pub fn sled_config() -> sled::Config {
+    sled::Config::default().use_compression(true)
+}