Clarify the situation on cpptasks in the documentation

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
site: Fix internal links to other pages

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add a helper to upload the documentation

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
upload-site: use Java 7 when possible

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
upload-site: add redirectors

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