- allow for multiple selection in STS..
- respect ordered subsetting from STS..
- STF.. now allows for a matrix index, but returns STS..
- STI.. allows now for multiple selection
Merge remote-tracking branch 'edzerRepo/master'
Merge remote-tracking branch 'edzerRepo/master'
Merge remote-tracking branch 'edzerRepo/master'
- added vignette on subsetting of spacetime classes
- some corrections of the subsetting methods along the way of the vignette
- some textual changes in stsubs.Rnw
- some textual changes in stsubs.Rnw
- updated test files for subsetting
- some textual changes

Merge branch 'master' of https://github.com/BenGraeler/spacetime

Conflicts:
	vignettes/stsubs.Rnw
	vignettes/stsubs.pdf
Merge pull request #17 from BenGraeler/master

Unified subsetting of ST* objects