Rollback to v1

[aler9]

Description

As discussed in #221, this reverts the library to /v1 by including only backward-compatible changes, in order to restore the release cycle of this library, that has been stuck for over a year.

In particular, i did the following:

1. the library was reverted to the last commit before bumping to v2 (4e87540)
2. all non-breaking commits from the v1 branch were cherry-picked
3. all non-breaking commits from the master branch were cherry-picked
4. the following breaking commits from master were edited and merged:

   • 150 - this removed some structs, that have been re-added and marked as deprecated

5. the following breaking commits were left out and will be readded with a PR in a non-breaking form:

   • 119

   • 160

[codecov[bot]]

Codecov Report

Patch coverage: 70.00% and project coverage change: -0.29 :warning:

Comparison is base (c5ca73a) 87.81% compared to head (5b8bbd2) 87.53%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #227 +/- ## ========================================== - Coverage 87.81% 87.53% -0.29% ========================================== Files 20 20 Lines 1863 1877 +14 ========================================== + Hits 1636 1643 +7 - Misses 197 204 +7 Partials 30 30 ``` | Flag | Coverage Δ | | |---|---|---| | go | `87.53% <70.00%> (-0.29%)` | :arrow_down: | | wasm | `86.57% <70.00%> (-0.28%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion) | Coverage Δ | | |---|---|---| | [codecs/av1\_packet.go](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#diff-Y29kZWNzL2F2MV9wYWNrZXQuZ28=) | `100.00% <ø> (ø)` | | | [codecs/h264\_packet.go](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#diff-Y29kZWNzL2gyNjRfcGFja2V0Lmdv) | `97.89% <0.00%> (-1.05%)` | :arrow_down: | | [codecs/opus\_packet.go](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#diff-Y29kZWNzL29wdXNfcGFja2V0Lmdv) | `88.23% <0.00%> (-11.77%)` | :arrow_down: | | [codecs/vp8\_packet.go](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#diff-Y29kZWNzL3ZwOF9wYWNrZXQuZ28=) | `89.93% <0.00%> (-1.15%)` | :arrow_down: | | [codecs/vp9\_packet.go](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#diff-Y29kZWNzL3ZwOV9wYWNrZXQuZ28=) | `94.87% <0.00%> (-0.82%)` | :arrow_down: | | [pkg/frame/av1.go](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#diff-cGtnL2ZyYW1lL2F2MS5nbw==) | `100.00% <ø> (ø)` | | | [packet.go](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#diff-cGFja2V0Lmdv) | `88.40% <95.00%> (+0.46%)` | :arrow_up: | | [packetizer.go](https://app.codecov.io/gh/pion/rtp/pull/227?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=pion#diff-cGFja2V0aXplci5nbw==) | `79.24% <100.00%> (+0.39%)` | :arrow_up: |

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[Sean-Der]

Fantastic! Thank you @aler9