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
fix
Update new combined graphviz image
errstr parameter in slug
CHECK_PTR macro to check pointer
slug_count return errstr
test incomplete slug
slug parser
fix pattern compiler
fix slug compile pattern
Merge branch 'master' into slugfix

Conflicts:
	tests/check_slug.c
update
Fix gvc graph
move slug related functions to slug.c and slug.h