Explore: Stop scanning when clear all button is clicked

Explore: return to grid layout for logs table

- better column control than flexbox
- increased gutter and row spacing

Fix prevent removing last grafana admin permissions

fixedUnit for Flow:l/min and mL/min

got stranged result with decimalSIPrefix

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

dataproxy: Override incoming Authorization header

Prevent password reset when login form is disabled or either LDAP or Auth Proxy is enabled

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