Fix to a minor fumble over SI prefixes, some internal refactoring, and minor API additions.

- Added new function max() to byteunit type.
- New public constant 'simplebyteunit::MAX' defining the maximum supported power.
- Output module to house arithmetic and prefix functions for output values.
- For the sake of SI compliance, kilobytes are now prefixed as 'kB'.

src/output.rs

@@ -0,0 +1,51 @@
+/*  
+ * SimpleByteUnit
+ * 
+ * Copyright 2023 Xaver R.M.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *	http://www.apache.org/licenses/LICENSE-2.0
+ */
+
+use crate::simplebyteunit::*;
+
+pub fn prefix<'a, T: Copy>(unit: &ByteUnit<T>, i: i8) -> &'a str {
+    match unit {
+        ByteUnit::IEC(_) => match i {
+            K => "KiB",
+            M => "MiB",
+            G => "GiB",
+            T => "TiB",
+            P => "PiB",
+            E => "EiB",
+            _ => "B"
+        },
+        ByteUnit::SI(_) => match i {
+            K => "kB",
+            M => "MB",
+            G => "GB",
+            T => "TB",
+            P => "PB",
+            E => "EB",
+            _ => "B"
+        }
+    }
+}
+
+pub fn arithmetic<T: Copy>(value: (T, f64), power_of: i8) -> (i8, f64) where i64: From<T> {
+    let bytes: i64 = value.0.into(); 
+    let diviser = value.1; 
+    let positive = bytes > -1;
+    let mut bytes: f64 = if positive { bytes } else { -bytes } as f64;
+    let mut power = 0;
+
+    while bytes >= diviser && power < power_of {
+        bytes = bytes / diviser; 
+        power += 1;
+    }
+ 
+    match positive { true => (power, bytes), false => (power, -bytes) }
+}