[main] rootbrowse: instance a TRint instead of TApplication

This gives 2 advantages: it executes .rootlogon.C on startup (like the
old rootbrowse did) and it provides an interactive prompt to the user
while using rootbrowse.

Author: silverweed

main/src/rootbrowse.cxx

@@ -9,7 +9,7 @@
 #include "logging.hxx"
 #include "optparse.hxx"
 
-#include <TApplication.h>
+#include <TRint.h>
 #include <TBrowser.h>
 #include <TError.h>
 #include <TFile.h>
@@ -106,7 +106,7 @@ int main(int argc, char **argv)
 
    // NOTE: we need to instantiate TApplication ourselves, otherwise TBrowser
    // will create a batch application that cannot show graphics.
-   TApplication app("rootbrowse", nullptr, nullptr);
+   TRint app("rootbrowse", nullptr, nullptr);
 
    if (!args.fWeb.empty())
       gROOT->SetWebDisplay(std::string(args.fWeb).c_str());