Support multiple populations.

Cargo.lock

@@ -1,5 +1,7 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+version = 3
+
 [[package]]
 name = "adler"
 version = "0.2.3"
@@ -388,6 +390,12 @@ version = "0.2.86"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b7282d924be3275cec7f6756ff4121987bc6481325397dde6ba3e7802b1a8b1c"
 
+[[package]]
+name = "libm"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7d73b3f436185384286bd8098d17ec07c9a7d2388a6599f824d8502b529702a"
+
 [[package]]
 name = "log"
 version = "0.4.14"
@@ -481,6 +489,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a64b1ec5cda2586e284722486d802acf1f7dbdc623e2bfc57e65ca1cd099290"
 dependencies = [
  "autocfg",
+ "libm",
 ]
 
 [[package]]
@@ -514,6 +523,7 @@ dependencies = [
  "indicatif",
  "itertools 0.10.0",
  "rand",
+ "rand_distr",
  "rayon",
 ]
 
@@ -612,6 +622,16 @@ dependencies = [
  "getrandom",
 ]
 
+[[package]]
+name = "rand_distr"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da9e8f32ad24fb80d07d2323a9a2ce8b30d68a62b8cb4df88119ff49a698f038"
+dependencies = [
+ "num-traits",
+ "rand",
+]
+
 [[package]]
 name = "rand_hc"
 version = "0.3.0"