Add security to Hidden Burn Variables by calling SecureZeroMemory on the value, encrypting the value, and adding SecureStringVariables to the managed Engine.
Make StringVariables use pointers so that the IBootstrapperEngineSecure interface can be deleted.
Consolidate the StrUtil Secure methods so the code isn't duplicated.
Formatting.
Ignore static content during help generation
Merge branch 'develop' of https://github.com/wixtoolset/wix3 into wixfeat4299
Fix bugs.
Merge branch 'develop' into help
Resolve pull request comments re: static content
WIXBUG:4215

Clarify all the elements that switch bitness based on
-arch/InstallerPlatform.
Add the WixBundleNumberOfApplyPhases built-in variable.
Add the MBAPrereqSupportPackage attribute to all package types so that more than one package can be installed by the Prereq BA.
Merge pull request #14 from heaths/help

Ignore static content during help generation
Merge pull request #25 from barnson/bug4215

Conflicts:
	History.md
Rename the MBAPrereqSupportPackage attribute to PrereqSupportPackage, the WixMBAPrereqSupportPackage table to MbaPrerequisiteSupportPackage, and respect the InstallCondition on the MbaPrereqPackage if the new attribute is set.
Convert WixBundleNumberOfApplyPhases variable to IBootstrapperApplication::OnApplyNumberOfPhases.
Merge pull request #6 from rseanhall/wixfeat4299

Conflicts:
	src/burn/engine/exeengine.cpp
Merge pull request #28 from rseanhall/feat4413

Conflicts:
	History.md
Merge pull request #30 from rseanhall/feat4161

Conflicts:
	History.md
WIXBUG:4418

Release strings and remove dead code.