Switch from net.imagej:ij to gov.nih.imagej:imagej

This prevents an indirect dependency on maven.imagej.net.
merge dev_5_0 -D org -I include -E exclude: PR 856 (Initial version of bfCheckJavaMemory)
merge dev_5_0 -D org -I include -E exclude: PR 867 (Ignore text nodes when parsing XMLAnnotation's value (rebased onto dev_5_0))
merge dev_5_0 -D org -I include -E exclude: PR 873 (Switch from net.imagej:ij to gov.nih.imagej:imagej)
merge dev_5_0 -D org -I include -E exclude: PR 874 (SDT: read each data block into a separate series (rebased onto dev_5_0))