Amend the build instructions to mention libsodium and default build only to mpw.

README.md

@@ -158,15 +158,27 @@ For example:
     ./build && sudo ./install
     mpw -h
 
-The build has a few dependencies you should have installed before running it:
+Normally, this is all you need to do, however note that there are a few dependencies that need to be met, depending on which targets you are building:
 
- - `mpw`: `openssl-dev`, `ncurses-dev` (if `mpw_color=1`)
- - `mpw-bench`: `openssl-dev`
- - `mpw-tests`: `openssl-dev`, `libxml2`
+ - `mpw`
 
-There are a few different ways you can modify the build process:
+The C implementation depends either on `libsodium` or Tarsnap's `scrypt` and `openssl-dev`.
 
- - You can change the targets that should be built.  By default, all targets are built.  These are the available targets:
+We recommend you install `libsodium`.  If `libsodium` is not installed when `./build` is executed, the script will try to download and statically link Tarsnap's `scrypt` instead.  Tarsnap's `scrypt` depends on you having `openssl-dev` installed.
+
+If you have `mpw_color` enabled (it is enabled by default), the build also depends on `ncurses-dev` to communicate with the terminal.
+
+ - `mpw-bench`
+
+This tool compares the performance of a few cryptographic algorithms, including bcrypt.  The `./build` script will try to automatically download and statically link `bcrypt`.
+
+ - `mpw-tests`
+
+This tool runs a suite of tests to ensure the correct passwords are being generated by the algorithm under various circumstances.  The test suite is declared in `mpw-tests.xml` which needs to exist in the current working directory when running the tool.  In addition, `libxml2` is used to parse the file, so this target depends on you having it installed when running `./build`.
+
+Finally, there are a few different ways you can modify the build process:
+
+ - You can change the targets that should be built.  By default, only `mpw` is built.  These are the available targets:
     - `mpw`: This is the standard command-line `mpw` tool which implements all Master Password features.
     - `mpw-tests`: This is a tool to perform the standard tests script on the `mpw` implementation.
     - `mpw-bench`: This is a tool to run a benchmark on the `mpw` implementation, comparing it to the performance of other algorithms.
@@ -176,7 +188,7 @@ There are a few different ways you can modify the build process:
 
 To change the targets to build, use:
 
-    targets='mpw mpw-bench' ./build
+    targets='mpw mpw-tests' ./build
 
 To add a library search path, use: