Implement issues 10 and 57

See issues #10 (closed) and #57 (closed).

scripts/larvatagger

@@ -52,7 +52,7 @@ import|merge|--version|-V)
 LarvaTagger
 
 Usage:
-  larvatagger open <file-path> [--backends=<path>] [--port=<number>] [--quiet] [--viewer] [--browser] [--view-factor=<real>] [--manual-label=<label>]
+  larvatagger open [<file-path>] [--backends=<path>] [--port=<number>] [--quiet] [--viewer] [--browser] [--view-factor=<real>] [--manual-label=<label>]
   larvatagger import <input-path> [<output-file>] [--id=<id>] [--framerate=<fps>] [--pixelsize=<μm>] [--overrides=<comma-separated-list>] [--default-label=<label>] [--manual-label=<label>] [--decode] [--copy-labels]
   larvatagger train <backend-path> <data-path> <model-instance> [--pretrained-model=<instance>] [--labels=<comma-separated-list>] [--sample-size=<N>] [--balancing-strategy=<strategy>] [--class-weights=<csv>] [--manual-label=<label>] [--layers=<N>] [--iterations=<N>] [--seed=<seed>] [--debug]
   larvatagger train <backend-path> <data-path> <model-instance> --fine-tune=<instance> [--balancing-strategy=<strategy>] [--manual-label=<label>] [--iterations=<N>] [--seed=<seed>] [--debug]
@@ -101,6 +101,7 @@ Commands:
 
   open      Launch the server-based GUI.
 
+    The optional positional argument <file-path> can also be the data root directory.
     Backends defined in LarvaTagger project root directory are automatically found. Other
     backend locations can be specified with the --backends argument.