Factor out file functions

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Factor out functions relating to the Java home

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Factor out the splash-screen code

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Factor out platform-dependent code

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Factor out the Windows-specific icon changing code

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
fixup! Factor out file functions
fixup! Factor out functions relating to the Java home
Factor out string array functions, too

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
TODO: refactor config, command-line parsing, subcommands

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>