Chisel - String Table

## Overview

This crate contains a very simple string table which can be used to intern strings by stashing them all within a single data-structure, and then referencing them throughout other areas of a code base using a unique u64 identifier.

Currently there is a single implementation of an interning data structure based on an internal B-Tree index. Nothing very sophisticated going on here at all.

### Usage

There really isn't much to it:

```rust use chiselstringtable::btreestringtable::BTreeStringTable; use chiselstringtable::common::StringTable;

 let mut table = BTreeStringTable::new();
 let key : u64 = table.add("some value to intern");
 assert_eq!(table.get(key).unwrap(), "some value to intern");
 assert_eq!(format!("Here's me embedded string: {}", table.get(key).unwrap()),
                     "Here's me embedded string: some value to intern")

```