feat(cli): docopt subcommands

Setup command/subcommand pattern.
Next will be the infrastucture for documenting these, using mkdocs
and markdown.

Author: Byron

src/mako/cli/lib/docopt.mako

@@ -1,22 +1,25 @@
 <%namespace name="util" file="../../lib/util.mako"/>\
+<%!
+    from cli import mangle_subcommand
+%>\
 <%def name="new(c)">\
 docopt!(Args derive Debug, "
-Usage: ${util.program_name()} [options] (<OUTPUT-FILE>|-)
-       ${util.program_name()} --help
+Usage: 
+    % for resource in sorted(c.rta_map.keys()):
+<%
+        mangled_method_names = [mangle_subcommand(method) for method in sorted(c.rta_map[resource])]
+        assert mangled_method_names
+%>\
+    ${util.program_name()} ${mangle_subcommand(resource)} \
+% if len(mangled_method_names) > 1:
+(\
+% endif
+${'|'.join(mangled_method_names)}\
+% if len(mangled_method_names) > 1:
+)\
+% endif
 
-Options:
---width <X>                    The width of the output image [default: 1024]
---height <Y>                   The height of the output image [default: 1024]
---samples-per-pixel <SAMPLES>  Amount of samples per pixel. 4 means 16 over-samples [default: 1]
---num-cores <NUM_CORES>        Amount of cores to do the rendering on [default: 1]
-                               If this is not set, you may also use the RTRACEMAXPROCS
-                               environment variable, e.g. RTRACEMAXPROCS=4.
-                               The commandline always overrides environment variables.
-
-<OUTPUT-FILE>|-     Either a file with .tga extension, or - to write file to stdout
-"
-, flag_samples_per_pixel: u16
-, flag_height: u16
-, flag_width: u16
-, flag_num_cores: usize);
+    % endfor # end for each resource
+    ${util.program_name()} --help
+");
 </%def>

src/mako/cli/main.rs.mako

@@ -11,7 +11,7 @@
 extern crate docopt;
 extern crate rustc_serialize;
 
-<%docopt:new c="c"/>\
+${docopt.new(c)}\
 
 fn main() {
     let _: Args = Args::docopt().decode().unwrap_or_else(|e| e.exit());

src/mako/lib/cli.py

@@ -0,0 +1,5 @@
+import util
+
+# transform name to be a suitable subcommand
+def mangle_subcommand(name):
+    return util.camel_to_under(name).replace('_', '-').replace('.', '-')