* feat: bump bootstrap version to 4.0.0-beta
part of #298
* feat: bump bootstrap version to 4.0.0-beta
update color map
part of #298
* chore: update variable mappings, regenerate API
* fix: use correct values for accent and accent-contrast
* fix(button): use correct values for button variables
* chore: update api docs after button varibles change
* chore: reorder base variables and regen docs
* chore: tweak base and button colors
* fix(node-variable): improve node hover state
* feat(pager): add variables for pager styling (#300)
* fix(inputs): update inputs colors
* feat: improve focus for panelbar and treeview items and improve $base and $header variables
* feat: improve variables
* feat(button): Add variable for adjusted button opacity
* fix(checkbox): fix wrong check color
* feat(fieldset): remove borders and spacing, add font-size to legend
* chore(progressbar): Remove chunk border, add default flag to height variable
* chore(progressbar): Restore chunk border
* fix(pager): update pager dropdown appearance
* fix(menu): make active item text to be visible
* fix(dropdowns): colorpicker, combobox and datetime widgets popup open state
* fix(grid): update appearance
* fix(inputs): update slider and switch appearance
* fix(popup): add states for list containers
* fix(menu): add focus state to items
* chore: use theme-colors override for bootstrap
* fix(menu): add active state to root items
* fix(variables): improve line-height-em units for proper elastic behavior
* feat(overrides): improve secondary color override variable
* fix(combobox): Improves combobox appearance
* chore: remove focus outline of k-select in pickers
* chore: change k-select border color in pickers
* chore: change -bg value to -100
* chore: change k-sate-selected for buttons and tools to match k-state-active for button
* chore: add focus outline to checkbox button group
* chore: use corret color for dialog button group
* chore: use correct focus outline for primary buttons in button group
* chore: improve grid colors
* chore: link tooltip arrow variables to tooltip-bg
* fix(datetimepicker): in certain cases IE11 squashes datetimepicker icons
* chore(grid): Adjust Grid alt and hover row opacity