Add BEJ tree API.

This API allows us to represent a JSON object with a linked list
representation.

Signed-off-by: Kasun Athukorala <kasunath@google.com>
Change-Id: I7894e7c10e4db2ad02a79b01bb4d7a48d5a197cd
diff --git a/src/meson.build b/src/meson.build
index c09268e..051b397 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -3,6 +3,7 @@
   'bej_decoder_core.c',
   'bej_common.c',
   'bej_dictionary.c',
+  'bej_tree.c',
   'bej_decoder_json.cpp',
   include_directories : libbej_incs,
   implicit_include_directories: false,