(cherry picked from commit 52dc14c3)

(cherry picked from commit 6148abb1)

(cherry picked from commit c8762544)

(cherry picked from commit e855ca45)

* Merge GSNContext into GSNRecipient

* Update GSNRecipient.test.js

* Update GSNRecipient.sol

* Make GSNRecipient inherit from Context

(cherry picked from commit 1efa9f62)

* Improve IRelayRecipient docs

* Fix link

* Update IRelayHub docs to the docsite format

* Update IRelayRecipient docs to the dociste format

* Fix typo

* Improve GSN readme

* Fix link

* Update GSNRecipient docs

* Apply suggestions from code review

Co-Authored-By: Andrew B Coathup <28278242+abcoathup@users.noreply.github.com>

* Apply suggestions from code review

Co-Authored-By: Andrew B Coathup <28278242+abcoathup@users.noreply.github.com>

* Apply suggestions from code review

Co-Authored-By: Andrew B Coathup <28278242+abcoathup@users.noreply.github.com>
(cherry picked from commit d8642286)

(cherry picked from commit 5274b3d8)

* Replace confirmRelayedCall with approveRelayedCall

* Update gsn-bouncers.adoc

* Update deprecated enums

(cherry picked from commit 9c733a7b)

(cherry picked from commit 4e527a20)

(cherry picked from commit 5d183d0e)

Fix typos in instructions

(cherry picked from commit 2836b066)

(cherry picked from commit d8a25d17)

(cherry picked from commit 5ec72049)

(cherry picked from commit 1e427498)

* Remove SignatureBouncer

* Update changelog entry

* Fix coverage

* Update CHANGELOG.md

* move gsn link

* change underscore to dash

* add content to gsn api ref

* change link of GSN announcement

* Update contracts/GSN/bouncers/GSNBouncerERC20Fee.sol

Co-Authored-By: Nicolás Venturo <nicolas.venturo@gmail.com>

* fix crossreference to gsn guide

* Remove intro from gsn guide

We are moving the intro to the top-level in the docsite, and focusing this guide into writing gsn-enabled contracts.

* Update docs/modules/ROOT/pages/gsn.adoc

Co-Authored-By: Francisco Giordano <frangio.1@gmail.com>

* Update gsn.adoc

* Update gsn_advanced.adoc

Line 15 - where it says, "prevent malicious users from spending the transactions subsidy", with transactions subsidy, is it supposed to be possessive "transaction's subsidy" or is the plural in the wrong place "transaction subsidies"?

Line 176 - where it says "or it is not allowed to spend that amount". Is IT referring to the sender/person or the tx? If IT refers to a person, then change to "or they are not allowed..." for gender neutral.

Line 213 - Where it says, "Please not how the gas cost estimation", a verb is missing, please what?

* Update gsn_advanced.adoc

Apply suggestions by Amy

(cherry picked from commit 5c19876f)

* switch to using Context internally

* add context import

* Add smoke test to make sure enabling GSN support works

* Update test/GSN/ERC721GSNRecipientMock.test.js

Co-Authored-By: Francisco Giordano <frangio.1@gmail.com>

* Upgrade truffle

* add missing awaits

* Revert "Upgrade truffle"

This reverts commit f9b0ba9019650fdbf8919a33e6fba834689e6b04.

> openzeppelin-solidity@2.3.0 lint /home/luiserebii/github/openzeppelin-solidity
> npm run lint:js && npm run lint:sol

> openzeppelin-solidity@2.3.0 lint:js /home/luiserebii/github/openzeppelin-solidity
> eslint .

> openzeppelin-solidity@2.3.0 lint:sol /home/luiserebii/github/openzeppelin-solidity
> solhint --max-warnings 0 "contracts/**/*.sol", alongside some minor grammatical corrections