binman: Convert to use ArgumentParser

This class is the new way to handle arguments in Python. Convert binman
over to use it. At the same time, introduce commands so that we can
separate out the different parts of binman functionality.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/README b/tools/binman/README
index ef62d1f..fe734c1 100644
--- a/tools/binman/README
+++ b/tools/binman/README
@@ -187,7 +187,7 @@
 
 Type:
 
-	binman -b <board_name>
+	binman build -b <board_name>
 
 to build an image for a board. The board name is the same name used when
 configuring U-Boot (e.g. for sandbox_defconfig the board name is 'sandbox').
@@ -195,7 +195,7 @@
 
 Or you can specify this explicitly:
 
-	binman -I <build_path>
+	binman build -I <build_path>
 
 where <build_path> is the build directory containing the output of the U-Boot
 build.
@@ -483,7 +483,7 @@
 For details on the various entry types supported by binman and how to use them,
 see README.entries. This is generated from the source code using:
 
-	binman -E >tools/binman/README.entries
+	binman entry-docs >tools/binman/README.entries
 
 
 Hashing Entries
@@ -715,7 +715,7 @@
 -------------
 
 Binman is a critical tool and is designed to be very testable. Entry
-implementations target 100% test coverage. Run 'binman -T' to check this.
+implementations target 100% test coverage. Run 'binman test -T' to check this.
 
 To enable Python test coverage on Debian-type distributions (e.g. Ubuntu):