Rename argument to model-file from filename.

Signed-off-by: James Goppert <james.goppert@gmail.com>

README.md

@@ -98,11 +98,11 @@ Type the following to test that rumoca is in your path.
 $ rumoca --help
 Rumoca Modelica Translator
 
-Usage: rumoca [OPTIONS] --template-file <TEMPLATE_FILE> --filename <FILENAME>
+Usage: rumoca [OPTIONS] --template-file <TEMPLATE_FILE> --model-file <MODEL_FILE>
 
 Options:
   -t, --template-file <TEMPLATE_FILE>  The template
-  -f, --filename <FILENAME>            The filename to compile
+  -m, --model-file <MODEL_FILE>        The model file to compile
   -v, --verbose                        Verbose output
   -h, --help                           Print help
   -V, --version                        Print version
@@ -116,7 +116,7 @@ This package uses the standard cargo conventions for rust.
 cargo build
 cargo run
 cargo test
-cargo run -- -t test/templates/casadi_sx.jinja -f test/models/integrator.mo 
+cargo run -- -t test/templates/casadi_sx.jinja -m test/models/integrator.mo
 ```
 
 This package uses the standard cargo installation conventions.
@@ -142,7 +142,7 @@ end Integrator;
 
 ### Generated CasADi output file.
 ```bash
-$ rumoca -t test/templates/casadi_sx.jinja -f test/models/integrator.mo 
+$ rumoca -t test/templates/casadi_sx.jinja -m test/models/integrator.mo
 ```
 ```python
 import casadi as ca

src/main.rs

@@ -13,9 +13,9 @@ struct Args {
     #[arg(short, long)]
     template_file: String,
 
-    /// The filename to compile
+    /// The model file to compile
     #[arg(short, long)]
-    filename: String,
+    model_file: String,
 
     /// Verbose output
     #[arg(short, long, default_value_t = false)]
@@ -24,7 +24,7 @@ struct Args {
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let args = Args::parse();
-    let def = s1_parser::parse_file(&args.filename);
+    let def = s1_parser::parse_file(&args.model_file);
     let mut flat_def = s2_analyzer::flatten(&def).expect("failed to flatten");
 
     if args.verbose {