Fix issue that causes atmosphere to show up on the other side of a planet if the shading is disabled (closes #677)

 * Add coordinate axes renderable
 * Add debug helper
 * Add example asset
 * Fix bug with dynamic loading of assets. (#763)

 * Merge experimental session recording branch
 * Merge new CEF-based webgui branch

  * Update node packages, download nodejs in build process, start server from openspace process
  * Patch CEF cmake automatically
  * Build webserver automatically
  * Work on CMake for WebBrowser, Webgui and CefWebGui
  * Map key modifiers to CEF
  * Smooth time interpolation in webgui
  * Automatically focus on search field in filter lists
  * Move webgui code to external repositories
  * Use asset system to distribute webgui
  * Remove webgui from main repository
  * Add support for right click in webgui and improve timetopic
  * Resolve cmake policy warning
  * Add relative time interpolation to lua interface
  * Sanitize json error message before logging error. Workaround for #736
  * Added gui properties to scene graph nodes
  * Add version topic
  * Add shortcuttopic
  * Add ability to disable rendering of cefwebgui
  * Don't do message loop work if there is no browser.
  * Set correct path to nodejs on unix
  * Message loop work in presync
  * modifications for shortcuts in gui, added names for shortcuts
  * Set properties via lua scripts
  * Allow gui grouping for shortcuts
  * Add gui paths keybindings
  * Blocking keyboard callbacks when webgui has keyboard focus in an editable field
  * Allow disabling of WebBrowser and CefWebGui
  * Make it possible to hide GUI
  * Get rid of redundant dashboard items if web gui is used
  * Hide WebGUI on slave nodes
  * Hide WebGUI on main rendering window if a GUI window exists
 * Enable WebGUI on default unless it is overwritten in the openspace.cfg
  * Add guiName for propery owners in socket api

Increase the default number of significant digits to 4

Prevent accidental walking of the current working directory when starting OpenSpace that could cause non Lua script files to be loaded as .info files

Remove all manual specification of caching and offline mode from manual wms servers

* In progress with new version of session recording

* Session recording coding pass for both record and playback, not building yet.

* Working on getting first build of prototype

* Code changes to get playback working with all 3 timing modes

* Fixing session recording interactions with the timemanager

* Bug fixes for newly discovered timing issues, mothballing recording of timing updates

* Fixed camera jitter issue

* Updated new reference to latest ghoul

* Got session recording/playback working with changes made in master

* Added threshold for differences in camera movement as criteria for saving to recording file

* Added support for binary file for session recording/playback

* Minor changes with handling timeManager keyframes in playback

* New timeline structure & keyframes specific to session recording

* Fixed bug with fixed-script size

* Switched to new timeline specific to session recording, bug fixes, currently debugging camera position & rotation

* Formatting changes only

* Fixed scripts not working after timeline change

* Add session recording test scene

* Fixed problem with re-running the same playback multiple times

* Fixed problems with camera interpolation

* Fixed detection of camera playback finishing, and improved camera interpolation

* Added comments for interface of externInteraction include

* Fixed view frustum culling issues in session playback due to not appropiate camera scaling. Also made function in datamessagestructures to read and write this data to streams.

* Added camera scaling fix to code that supports Ascii format

* Added startPlayback default command for playing back while forcing simulation time to match the recording

* Fixed camera jump in sessionRecording after playback finished. Cleanup in playback of camera to re-use same functionality in keyframenavigator.

* Superb fix to sessionRecording. Realized focusNode of globalNavigationHandler needed to be activly update when camera change for either position of camera to be accurate or for rendered objects to be calculated without precision issues. Can now achieve a correct playback, even close to chunks/renderable, which was not possible before.

* sessionRecording cleanup, fixed all warnings and renamed files to lowercase to match current standards.

* Added error handling for bad input playback filename, protection from corrupted playback file

* Implemented code review changes on pull request #737 for sessionRecording

Update GDAL to 2.3.2