Graal instructions for Eclipse + Checkstyle + Java7

[Raffaello Giulietti]

Hi,

the Graal instructions for Eclipse
(https://wiki.openjdk.java.net/display/Graal/Eclipse) explain how to
import the projects in the $GRAAL folder into Eclipse (I think it is
denoted as the primary suite in mx terms).

However, they fail to mention that the sibling folders $GRAAL/../jvmci
and $GRAAL/../truffle should also be imported in the same vein.
Otherwise, Eclipse complains about 1000 and more missing dependencies.

Further, if the Checkstyle plugin is installed in Eclipse, it complains
about redundant private modifiers on many classes and marks them as
errors. Since Checkstyle is specified as builder in the meta-information
generated by "mx eclipseinit"
* it should be dropped from there (short-term quick'n'dirty solution)
* or the source code of the "misbehaving" classes be corrected
appropriately (mid-term clean solution)

Finally, many Truffle projects still specify JavaSE-1.7 in their build
path. Eclipse signals these as warnings if Java 7 is not installed on
the system.


Greetings
Raffaello