1.4.0 Alpha - Gradle plugin overhaul

Main features:

• Gradle plugin overhaul
• Autoconfiguration for sourceset for Multiplatform projects
• Kotlin 1.4.0

Improvements:

Html format:

• added left navigation search component
• improved intuitiveness of displayed cursor types (thanks to @hamza1311)
• improved presentation of some generic parameters
• made unresolved links render as text
• improved overall UI experience

Javadoc:

• implemented generating both package-list and element-list
• added index page

Reporting

• maturity warning
• handling of missing sourceset for Javadoc
• handling nothing to document
• descriptions to all Dokka tasks

Other:

• improved parsing of generic typealiases
• removed redundant type bounds from all formats

Bugs fixed:

• missing whitespace in class-like signatures - #1419
• classpath issues in very specific conditions - #1415
• missing resources on windows - #1399
• top-level functions crashing Javadoc generation - #1393 #1385
• unstable order of functions in generated documentation - #1333
• anchors on android being broken in some cases - #1230
• improperly formatted code blocks - #1346
• source tabs not displayed on Windows in html format - #1361
• stack overflow on documenting complex type constraints - #1342
• symbols defined in companion objects not being linked correctly in rare cases - #1268
• unresolved links in some cases - #1345
• missing sourcesets on non-lazily configured Android projects - #1330
• Couldn't get delegate for class error - #1341
• to many sources set bubbles after running Dokka collector - #1294
• empty packages listed in the sidebar - #1257
• suppressed files still documented - #1245