Analyser API should be improved

[Ducasse]

Currently MicAnalysisReportWriter is invoking the analyser as follows:

reportForFolder: folderReference startingFrom: fileReference
	"I perform several analyses starting from a root document file reference (e.g. index.md)"

	"In the future we should have a better way to add analysis. "	
	| reporter checker validator |
	reporter := self new.

	checker := MicReferenceChecker new.
	checker fileSystem: folderReference.
	checker checkProject: fileReference.

	reporter addResults: checker results.

	validator := MicCodeBlockValidator new.
	checker fileSystem: folderReference.
	checker checkProject: fileReference.

	reporter addResults: validator results.
	^ reporter

• we will need a better way to handler analyser registration
• but also checkProject: is reparsing and recollecting all the files so we should provide another API so that we can pass simply an object tree representing the document.