JBDS-3152 - Cheatsheet crashes silently when they need to open files
JBIDE-18381 : better lazy initialization of properties

Signed-off-by: Fred Bricon <fbricon@gmail.com>
JBIDE-18411 - bad parsing, assuming a dot and suffix in url
JBIDE-18411 - added unit test
JBIDE-18412 - aggressive caching for stacks
JBIDE-18412 - further fallback and exception handling
JBDS-3159 Usage dialog is not displayed for user after initial install
Remove duplicate code

Signed-off-by: Fred Bricon <fbricon@gmail.com>
JBIDE-18340 NullPointerException occures when opening properties file from external jar

In case of a link in Linux, java.io.File.equals returns false,
if instance with absolute path is compared to an instance with
an alias in its path. It is only safe to compare canonical paths.
JBIDE-18446 - cache on github should be outdated due to 0 remote timestamp