* Bump version to new release: 2.0.0
  We do this, because the changes in this patch fundamentally
  alter the way code is generated by the tool. This will, in some
  cases, be incompatible with older versions.
* Performs cleanup and minor code fixes.
* Adds two new command line flags:
  * -prefix: This accepts a partial path. It is used when generating
    a target function name, as well as the key for the Table of Contents
    map (see below). The specified prefix is applied to the input
    file name, causing the prefix section to be stripped from the
    input file path. E.g.:
    ```
    input: /path/to/foo.x
    prefix: /path/to
    output: /foo.x
    ```
  * -toc: This is a boolean flag which tells the tool to generate
    a table of contents for the generated data files. It creates
    a separate 'bindata-toc.go' file, which defines a global map
    named `go_bindata`. It then appends an `init` function to the
    generated file. This function makes the data function register
    itself with the global map.
* Fixes the function names the tool infers from input file names
  to include the full path. This fixes potential name collisions
  when the same file name is processed from different directories.
  For example, we can now safely import the following two files:
  ```
   input file: css/ie/foo.css
   output function: css_ie_foo_css()

   input file: css/chrome/foo.css
   output function: css_chrome_foo_css()
  ```