* Fix: line chart with category x-axis: when some values missing, wrong hints displayed on hover
* Fix: second Y-axis not displayed when stacking enabled
* Set of dashboard improvements and bug fixes
- set minimal height of widgets to 1 (was 4)
- bug: for some widgets auto-height wasn't calculated properly (sometimess too small, sometimes too large)
- bug: for small widgets, top-right menu was cut to widgets bounds
- bug: with opened top-right menu widgets with auto-height started "dancing"
- bug: at some point auto-height feature was disabling by itself (in fact - it depends on `angular-grindter`s internal processes)
- fix: widget with empty contents had extra 40px of white space (paddings of container)
* Add scrollbars to pivot table widgets
* Fix: 100% CPU loading caused page lags
