Improved numerical integral for regression

Fixes #19
updated NEWS
Merge branch 'issue19'
Merge pull request #20 from richarddmorey/issue19

Issue19
Add checking for missing data

Fixes #18
Merge pull request #21 from richarddmorey/issue18

Add checking for missing data
Delete BayesFactor_0.9.8.tar.gz

Accidentally added this file...
Merge branch 'master' of https://github.com/richarddmorey/BayesFactor
Improved integration in unbalanced one-way ANOVA

fixes #22
Merge pull request #23 from richarddmorey/issue22

Improved integration in unbalanced one-way ANOVA
added callback for meta.t sampling
callbacks called from meta.ttestBF
removed (inappropriate) callback from meta.ttestBF
meta.ttestBF callbacks operational
added support for callbacks in some C functions

(callbacks are still inoperable, however)
fixes after rebase from master
Merge branch 'JASPcallbacks' of https://github.com/richarddmorey/BayesFactor into JASPcallbacks

Conflicts:
	pkg/BayesFactor/R/ttestBF.R