Roadmap for release 0.4

[JanMarvin]

This will be release 0.4 A release with moderate new features such as customXml support and minor bugfixes and should be the third released to CRAN.

Initially i was planing with a new release after Christmas holidays, but the speedups in #423 and the already merged PR justify an earlier release. I'm currently planing with a release at the end of the month.

open pull requests to merge

• tweaks for dates. #424 (could use some more QA testing)
• speedup numfmt assignment #423 (could use some more QA testing)
• [wbWorkbook] set_bookview #410
• Set sheetview #399

issues to work on pre release

• Avoid character returns in wb functions #378 (do you want to have a look at this @jmbarbone or shall we simply close this issue?)
• add printerOption modifications #393 (haven't heard back from @ycphs, but I have a look and open a PR for this)
• provide add_drawing() for {rvg} #449
• Support {mschart} #412 Support {mschart} #451

[JanMarvin]

We are on the finish line for 0.4. There are just two minor PR to merge, #399 and #440. Other than that we are in good shape and should be able to release this week.

[JanMarvin]

Now that mschart 0.4 has been released to CRAN I'm wiling to see if I can squeeze in a short time frame to include #449 and #412. #449 provides some extended add_drawing() features #412 can use, though I already had a few other plans (aside from working on charts).

[JanMarvin]

If all goes well, #451 is the last open PR to be merged prior the 0.4 release.