Minor release

This release contains some important fixes and minor enhancements, listed below:

News:
#216 Persist any new dataSource locations chosen by user (Luís Nassif)
#215 Print full timestamp for each WhatsApp message in chat html (Luís Nassif)
#214 Periodically log items being processed when using --nogui (Luís Nassif)
#203 Warn Linux users about need to install graphviz for graph layouts (Luís Nassif)
#207 Automatic CI jobs for newer java versions and upload java8 snapshot builds (Luís Nassif)
#217 Disable addToGraph menu option for items not related to communications (Luis Nassif)
Fixes:
#209 Error creating report in version 3.18.1 (Luís Nassif)
#218 Error generating graph in reports (Luís Nassif)
#212 Sorting results by some single valued columns never ends in 3.18.1 (Luís Nassif)
#213 Phones incorrectly decoded from email addresses and user accounts (Luís Nassif)
#210 Case remains image dependent when using blind profile w/ enableHtmlReport off in 3.18 (Luís Nassif)
#204 Gallery image click not working with openJDK8 on Linux (Luís Nassif)
#211 Right click on table regression in 3.18 and 3.18.1 on Linux (Luís Nassif)