Imports of callgraph command

PathSynopsis
bufioPackage bufio implements buffered I/O. It wraps an io.Reader or io.Writer object, creating another object (Reader or Writer) that also implements the interface but provides buffering and some help for textual I/O.
bytesPackage bytes implements functions for the manipulation of byte slices.
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
go/buildPackage build gathers information about Go packages.
go/tokenPackage token defines constants representing the lexical tokens of the Go programming language and basic operations on tokens (printing, predicates).
golang.org/x/tools/go/buildutilPackage buildutil provides utilities related to the go/build package in the standard library.
golang.org/x/tools/go/callgraphPackage callgraph defines the call graph and various algorithms and utilities to operate on it.
golang.org/x/tools/go/callgraph/chaPackage cha computes the call graph of a Go program using the Class Hierarchy Analysis (CHA) algorithm.
golang.org/x/tools/go/callgraph/rtaThis package provides Rapid Type Analysis (RTA) for Go, a fast algorithm for call graph construction and discovery of reachable code (and hence dead code) and runtime types.
golang.org/x/tools/go/callgraph/staticPackage static computes the call graph of a Go program containing only static call edges.
golang.org/x/tools/go/packagesPackage packages loads Go packages for inspection and analysis.
golang.org/x/tools/go/pointerPackage pointer implements Andersen's analysis, an inclusion-based pointer analysis algorithm first described in (Andersen, 1994).
golang.org/x/tools/go/ssaPackage ssa defines a representation of the elements of Go programs (packages, types, functions, variables and constants) using a static single-assignment (SSA) form intermediate representation (IR) for the bodies of functions.
golang.org/x/tools/go/ssa/ssautil
ioPackage io provides basic interfaces to I/O primitives.
logPackage log implements a simple logging package.
osPackage os provides a platform-independent interface to operating system functionality.
runtimePackage runtime contains operations that interact with Go's runtime system, such as functions to control goroutines.
text/templatePackage template implements data-driven templates for generating textual output.