trial merge of JS-applet to JS-develop 18th Oct 2019

.classpath, build.xml, buildcore.xml not in JS-develop (now gradle)
/swingjs moved in gradle workspace to ??
resources, libjs - also?

conflicts
tests
 ChimeraCommandsTest	formatting only?
 AlignFrameTest		setup/teardown location, Desktop.getInstance(); vq JAL-3453
 SeqPanelTest		change to testFindColumn_unwrapped
 BackupFilesTest	setBackupFilesOptions() diffs
 FeaturesFileTest	fixLineEnd() calls added JAL-3258
src
 FeatureDistanceModel	getDeclaredConstructor JS-develop
 Cache			various
 Jalview		getdown changes, vamsas removal / new constants
 JalviewLite		valueOf / scrollTo api (x3)
 SequenceFeatures	imports only
 EnsemblMap		GeneLocus /
 EnsemblRestClient	unresolved imports HttpMethod, ParseException
 Desktop		--vamsas / ApplicationSingletonProvider and several more...
 FeatureSettings	++refreshDisplay() / ++cancel()
 FeatureTypeSettings	Dingbats character
 IdPanel		JAL-3093 popup menu changes / comment only
 OverviewCanvas		draw() parameter type
 PCAPanel		/ just comments removed?
 PopupMenu		constructor javadoc
 Preferences		backups changes / setPropertyNoSave
 VamsasApplication	disableGui commented out / getInstance()
 WsPreferences		valueOf / getInstance
 GPreferences		/ (top level!) classes added
 FeatureRenderer	imports, drawSequence, complement/transparent minor conflicts
 StructureSelectionManager	++release() / 
 Platform		++pathEquals / lots of added methods