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/util/platform.rs

@@ -0,0 +1,60 @@
+//! Platform-related code
+use daedalus::minecraft::{Os, OsRule};
+use regex::Regex;
+
+// OS detection
+pub trait OsExt {
+    /// Get the OS of the current system
+    fn native() -> Self;
+}
+
+impl OsExt for Os {
+    fn native() -> Self {
+        match std::env::consts::OS {
+            "windows" => Self::Windows,
+            "macos" => Self::Osx,
+            "linux" => Self::Linux,
+            _ => Self::Unknown,
+        }
+    }
+}
+
+// Bit width
+#[cfg(target_pointer_width = "64")]
+pub const ARCH_WIDTH: &str = "64";
+
+#[cfg(target_pointer_width = "32")]
+pub const ARCH_WIDTH: &str = "32";
+
+// Platform rule handling
+pub fn os_rule(rule: &OsRule) -> bool {
+    let mut rule_match = true;
+
+    if let Some(ref arch) = rule.arch {
+        rule_match &= match arch.as_str() {
+            "x86" => cfg!(any(target_arch = "x86", target_arch = "x86_64")),
+            "arm" => cfg!(target_arch = "arm"),
+            _ => true,
+        };
+    }
+
+    if let Some(name) = &rule.name {
+        rule_match &= &Os::native() == name;
+    }
+
+    if let Some(version) = &rule.version {
+        if let Ok(regex) = Regex::new(version.as_str()) {
+            rule_match &=
+                regex.is_match(&sys_info::os_release().unwrap_or_default());
+        }
+    }
+
+    rule_match
+}
+
+pub fn classpath_separator() -> &'static str {
+    match Os::native() {
+        Os::Osx | Os::Linux | Os::Unknown => ":",
+        Os::Windows => ";",
+    }
+}