Misc styling fixes to explore: start page, slate code editor colors, text highlight in auto completeter suggestion

Add support for offset in date histogram aggregation

Explore: Fix logging query parser for regex with quantifiers

Explore: Show logging errors from backend

Fix misspelling issues using locale US

change obj order when merging so that correct format is being used

Fix mysql $__timeFrom() and $__timeTo() should respect local time zone

Update README.md

Explore: Fix label and history suggestions

- Logging datasource sends error string directly in the message body
- allowing response body to be an error when query transaction failed
- added throw in case we ever encounter unhandled errors again (forces us to fix the issue)

- ensure that selectors have to be preceded by whitespace or line beginning
- glacing over the fact that ` {0,1}` could be a valid regexp, but we're using space as query/regexp separators anyway, so I think it's fine for now

Explore: Logging render performance

- fork promql's tokenizer (need to specify that labels context can only follow beginning of line or whitespace)
- remove unneeded syntax features
- only present history items when field is empty

- fixed typo
- moved result calculation to explore utils
- use component keys instead of componentWillReceiveProps
- require logs to have and id, to as use as Logs component key
- render delay based on row count

Add AWS/CodeBuild namespace for CloudWatch datasource

add notice to MacOS Docker user, if docker  memory limit is less than 2GiB, build process may fail when run ./node_modules/.bin/grunt build

See,
$ find . -type f | xargs misspell -locale US | grep -vi -e vendor -e node_modules -e devenv -e unknwon -e destory -e yarn -e adn -e Spindel

See,
$ find . -type f | xargs misspell -locale US | grep -vi -e vendor -e node_modules -e devenv -e unknwon | grep docs

See,
$ find . -type f | xargs misspell -locale US | grep -v -e vendor -e node_modules -e devenv | grep CHANGELOG.md
./CHANGELOG.md:163:60: "organisation" is a misspelling of "organization"
./CHANGELOG.md:286:13: "Litre" is a misspelling of "Liter"
./CHANGELOG.md:394:163: "Spindel" is a misspelling of "Spindle"
./CHANGELOG.md:421:51: "metre" is a misspelling of "meter"
./CHANGELOG.md:738:73: "dashboad" is a misspelling of "dashboard"
./CHANGELOG.md:903:18: "organisation" is a misspelling of "organization"
./CHANGELOG.md:1031:48: "organisation" is a misspelling of "organization"
./CHANGELOG.md:1170:51: "cancelled" is a misspelling of "canceled"
./CHANGELOG.md:1874:97: "muliple" is a misspelling of "multiple"
./CHANGELOG.md:1909:60: "fullscren" is a misspelling of "fullscreen"

- moved from grid to flexbox
- calculate Explore results only when query transactions change to prevent expensive re-renders
- split up rendering of graph and log data
- render log results in 2 stages

Explore: Logging label filtering

removed extra whitespace

added google_tag_manager_id from defaults.ini

removed extra whitespace

Update export_import.md

Grafana v5.3.4 shows a new checkbox in the export modal "Export for sharing externally". If the checkbox is not checked then the "__inputs" section wont be included into the exported JSON file, would be great to add that note into the documentation for others to avoid confusions.

- adds a custom label renderer to Logs viewer in Explore
- labels are no longer treated as strings, they are passed as parsed objects to the log row
- label renderer supports onClick handler for an action
- renamed Explore's `onClickTableCell` to `onClickLabel` and wired up log label renderers
- reuse Prometheus `addLabelToSelector` to modify Logging queries via click on label
- added tests to `addLabelToSelector`, changed to include the surrounding `{}`
- use label render also for common labels in the controls panel
- logging meta data section has now a custom renderer that can render numbers, strings, and labels
- style adjustments

Logging: fix query parsing for selectors with multiple labels