jid: use textutil for escaping/unescaping

benchmark                        old ns/op     new ns/op     delta
BenchmarkEscapeTransform-4       64.7          172           +165.84%
BenchmarkUnescapeTransform-4     183           312           +70.49%
BenchmarkEscapeBytes-4           556           361           -35.07%
BenchmarkUnescapeBytes-4         257           388           +50.97%

benchmark                        old allocs     new allocs     delta
BenchmarkEscapeTransform-4       0              0              +0.00%
BenchmarkUnescapeTransform-4     0              0              +0.00%
BenchmarkEscapeBytes-4           3              3              +0.00%
BenchmarkUnescapeBytes-4         2              2              +0.00%

benchmark                        old bytes     new bytes     delta
BenchmarkEscapeTransform-4       0             0             +0.00%
BenchmarkUnescapeTransform-4     0             0             +0.00%
BenchmarkEscapeBytes-4           96            96            +0.00%
BenchmarkUnescapeBytes-4         48            48            +0.00%
Use dep for vendoring
jid: improve package docs

[ci skip]
xmpp: provide examples of stream features in docs

[ci skip]
xmpp: clarify stream features docs

[ci skip]
stanza: clarify and reword custom stanza docs

[ci skip]
xmpp: minor clarification in BindResource docs

[ci skip]
xmpp: rework BindCustom documentation

Minor refactor of bind to extract logic and make the source a bit easier
to read by separating the API from the implementation and putting the
long function full of all the logic at the bottom of the file.
stanza: add documentation about stanza creation

Fixes #37
stanza: add example of XMPP ping

Updates #37
stanza: remove innerxml fields from stanzas

Fixes #36
xmpp: fix misleading docs on StreamFeature
internal: add an XML helper for getting attributes
xmpp: fix broken rebase of server side bind
xmpp: support server side of resource binding

Also make test output for bind tests easier to read.

Fixes #14
xmpp: add contribution licensing notice to README
stanza: rename "StanzaError" to "Error"

Now that StanzaError has been moved into the stanza package it
introduced unnecessary stutter.
stream: fix package name in documentation

[ci skip]
stanza: move stanza functionality into new package
xmpp: make Serve a method on Session

Fixes #31
remove old .gitignore entries

[ci skip]