code: add curl

.gitignore

@@ -3,3 +3,4 @@
 /*.layout
 /*.depend
 /*.o
+/curl

main.cpp

@@ -1,5 +1,6 @@
 #include <iostream>
 #include <vector>
+#include <curl/curl.h>
 #include "histogram.h"
 #include "text.h"
 #include "svg.h"
@@ -36,6 +37,7 @@ Input input_data(istream& stream, bool prompt) {
 
 int main()
 {
+    curl_global_init(CURL_GLOBAL_ALL);
     Input in = input_data(cin, false);
     vector<size_t> bins = make_histogram(in.numbers, in.bin_count);
     show_histogram_svg(bins);