Merged VisualStudioLocator.getDefaultInstall() into locateVisualStudioInstalls(), and WindowsSdkLocator.getDefaultSdk() into locateWindowsSdks(). Changed VisualCppToolChain to locate each just once and remember the result.
Changed clients of VisualStudioInstall to use VisualCppInstall instead.
Ignore the default registry value when searching for visual studio installs.