implement clipboard on OSX, fix hex and rob sliders on picker

PanoPainter-OSX/main.cpp

@@ -24,6 +24,18 @@ std::mutex task_mutex;
 {
     NSSharingService *airdrop_service;
 }
+- (std::string)clipboard_get_string
+{
+    NSString* ns = [[NSPasteboard generalPasteboard] stringForType:NSPasteboardTypeString];
+    const char* ptr = [ns cStringUsingEncoding:NSUTF8StringEncoding];
+    return std::string(ptr);
+}
+- (bool)clipboard_set_string:(const std::string &)s
+{
+    NSString* ns = [NSString stringWithUTF8String:s.c_str()];
+    [[NSPasteboard generalPasteboard] setString:ns forType:NSPasteboardTypeString];
+    return true;
+}
 - (void)hockeyapp_crash
 {
     [[[BITHockeyManager sharedHockeyManager] crashManager] generateTestCrash];