Frontend extensions

[skip ci]

fix phantomjs render of graph panel when legend displayed as table to the right

Adding loading spinner to org pages

[skip ci]

elasticsearch: fix no limit size in terms aggregation for alerting queries

bug fix

fix alert no data when elasticsearch group by terms size is set to no limit

[skip ci]

Run queries for sql data sources for panels with multiple queries concurrently
Also make max open connections, max idle connections and max connection 
lifetime configurable in the data source settings

Explore: highlight typed text in suggestions

wip: whats new for 5.3

Plus a few tweaks to the text

Update mac.md

Update windows.md

Update rpm.md

[skip ci]

[skip ci]

cloudwatch: automatically set graph yaxis unit 

fixes #13575

This will stop a segfault from happening

Render Dashboard Row drag handle only in edit mode

fix CloudWatch id validation

Update debian.md