added development eclipse dropins to target platform search path

fortiss-std-env/buckminster/buckminster.target

 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <?pde version="3.6"?>
 
-<target name="buckminster-target" sequenceNumber="1">
+<target name="buckminster-target" sequenceNumber="2">
 <locations>
 <location path="${workspace_loc}/fortiss-std-env/target-platform" type="Directory"/>
 <location path="${eclipse_home}" type="Profile"/>
 <location path="${workspace_loc}/fortiss-std-env/delta-pack" type="Directory"/>
+<location path="${eclipse_home}/dropins" type="Directory"/>
 </locations>
 </target>