ZPAQ levels 1 and 2 now supported

[pete4abw]

See #117

in Reader class not properly referenced in libzpaq.cpp. Now all ZPAQ compression levels are used, 1-5.

diff --git a/src/lib/libzpaq/libzpaq.cpp b/src/lib/libzpaq/libzpaq.cpp
index 7bf3673..d343f93 100644
--- a/src/lib/libzpaq/libzpaq.cpp
+++ b/src/lib/libzpaq/libzpaq.cpp
@@ -2148,7 +2148,7 @@ int Decoder::decompress() {
   }
   else {
     if (curr==0) {
-      for (int i=0; i<4; ++i) curr=curr<<8|get();
+      for (int i=0; i<4; ++i) curr=curr<<8|in->get();
       if (curr==0) return -1;
     }
     --curr;