Imports of docgen 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.
embedPackage embed provides access to files embedded in the running Go program.
errorsPackage errors implements functions to manipulate errors.
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/mmcloughlin/avo/tests/thirdpartyPackage thirdparty executes integration tests based on third-party projects that use avo.
logPackage log implements a simple logging package.
mathPackage math provides basic constants and mathematical functions.
net/urlPackage url parses URLs and implements query escaping.
osPackage os provides a platform-independent interface to operating system functionality.
regexpPackage regexp implements regular expression search.
strconvPackage strconv implements conversions to and from string representations of basic data types.
stringsPackage strings implements simple functions to manipulate UTF-8 encoded strings.
text/templatePackage template implements data-driven templates for generating textual output.