Propagate an explicit denominator to the builder when creating d4 file

d4tools/src/create/main.rs

@@ -257,6 +257,7 @@ impl CreateAppCtx {
 
     fn determine_default_denominator(&mut self, matches: &ArgMatches) -> Result<(), DynErr> {
         if self.denominator.is_some() {
+            self.builder.set_denominator(self.denominator.unwrap());
             return Ok(());
         }
 

d4tools/test/create/fractional-bedgraph-fixed-denominator/cmdline

@@ -0,0 +1,2 @@
+${D4TOOLS} create --denominator 100 -g genome.size input.bedgraph ${OUTDIR}/out.d4 && \
+		${D4TOOLS} view ${OUTDIR}/out.d4

d4tools/test/create/fractional-bedgraph-fixed-denominator/genome.size

@@ -0,0 +1,2 @@
+chr1	1000
+chr2	1000

d4tools/test/create/fractional-bedgraph-fixed-denominator/input.bedgraph

@@ -0,0 +1,2 @@
+chr1	100	200	0.2
+chr2	300	400	10.8

d4tools/test/create/fractional-bedgraph-fixed-denominator/output.txt

@@ -0,0 +1,6 @@
+chr1	0	100	0
+chr1	100	200	0.2
+chr1	200	1000	0
+chr2	0	300	0
+chr2	300	400	10.8
+chr2	400	1000	0