Updates to progress bar API

test/bar.cpp

@@ -0,0 +1,27 @@
+#include <iostream>
+#include <progress/bar.hpp>
+
+int main() {
+  ProgressBar bar;
+
+  // Configure progress bar
+  bar.bar_width(100);
+  bar.start_with("[");
+  bar.fill_progress_with("=");
+  bar.lead_progress_with(">");
+  bar.fill_remainder_with(" ");
+  bar.end_with("]");
+
+  // As configured, the bar will look like this:
+  // 
+  // [=================>         ] 70%
+  //
+  //
+
+  for (size_t i = 0; i < 101; i += 5) {
+    bar.set_progress(i);
+    std::this_thread::sleep_for(std::chrono::milliseconds(1000));
+  }
+
+  return 0;
+}