Improvements in workflow, allow linter failure and don't stop build matrix on single os failure and add missing linter trigger on PRs

* Add github action files and remove travis files

* Suppress train tests in github actions

Remove markdown lint from travis.

Spelled "stopping" correctly

feat: enables to store position, gyro, accel, vel of simulator car in tub files

Co-authored-by: Meir Tseitlin <mirots@gmail.com>

Co-authored-by: Meir Tseitlin <mirots@gmail.com>

Reverting JOYSTICK_THROTTLE_DIR to v3 default

Set USE_JOYSTICK_AS_DEFAULT to False in cfg_complete.py

In v3 it is `-1.0`.

Improvements in tub and training to manage new datastore and new tub GUI

Fix tflite input/output conversion.

Add performance monitor

This is the default in v3. Setting this to `True` by default will not activate the web controller and caused some confusion to users.

myconfig.py default scene name fix

Add back training history plot

Patch to #752 - fix wrong operator in pip.

Add missing `DEFAULT_AI_FRAMEWORK`. `donkey train` won't run without this.

* Rename ubuntu.yml to pc.yml and update docs accordingly.

* Added missing update in travis.

Fixed FindCar function for RPi4

* Renamed function for session id creation in manifest and stored dictionary of last_id, last_full_id and all_full_ids in the metadata so no parsing needs to happen. Added more comment to the manifest to explain the session id logic. Added `if` around session_id update flag, so flag gets set only once.
* Reverted tub test and created new tub writer test instead
* Removed shutdown hook from tub writer as it will be closed by the vehicle
* When session_id data gets inserted into the metadata, only modify the corresponding line (actually the seekable also modifies the lines below, there is still room for improvement in that method)
* Minor performance upgrades and improved timing in fast forward loop in UI

* Fixed manifest iterator to avoid too deep recursive function calls which segfaults when deleting many records
* Automatic addition of '_session_id' field in the Tub. This mimics the naming convention we used to have for old-style tubs before: YY-MM-DD_N, where N is a running integer. All session ids of a tub are stored in the manifest.json file. The tub needs to receive records and needs to get closed for this entry to be updated.
* Added test for the new tub and tub writer logic

Tub GUI development:
* Support starting from 'donkey ui' command
* All relevant settings are stored in ~/.donkeyrc file which is editable

Training improvements:
* You can now put a predicate for tub records into the myconfig.py to filter records for training. The config variable TRAIN_FILTER has to be set to that function.
* Improve training performance by using tf prefetch
* Default AI framework to 'tensorflow' in training

Others:
* Update docs
* Update patch version number to 4.2.0
* Reduced run time of test_train using only 5 epochs and adjusting thresholds accordingly
* Reduced run time of torch tests using 3 epochs - these were very slow (like 25+ m on MacBook)
* Minor updates in docstrings and switching to f-strings
* Fixed duplicated function in keras.py

Co-authored-by: Chris Anderson <gca2@earthlink.net>