Wrap add/insert/delete page calls in begin/end operation.
Wrap add/insert/delete page calls in begin/end operation.

Without this commit an exception will be thrown e.g. in mutool run
scripts when doc.addPage() is called without a preceeding
doc.beingOperation() call , and this shouldn't be required.

ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf,ArtifexSoftware/mupdf