reduce variables and add const char* to insert_pathl.
remove unused variables
fix tests for graphviz
gvc fix
add const to node
Add AC_PROG_INSTALL
Add extern "C".
Merge pull request #44 from whitglint/master

Add extern "C".
build with 3rdparty objects

use -static linking when linking libr3

AM_CFLAGS and AM_LDFLAGS are Makefile.am scope options

disable valgrind tracing check-tree

Makefile.am fix

Add json support

remove useless c files
take off useless header files
include config.h
fix configure options:

1. fix --enable-json
2. fix --enable-graphviz
remove trailing newline
Merge branch 'feature/json'
Merge branch 'master' of github.com:c9s/r3

Conflicts:
	include/r3.h