do some preparation work

- establish BMapSharp project for future development.
- refactor EnumsMigration. add csharp code output for it.
- add README for VectorGen and modify other READMEs.

CodeGen/EnumsMigration/README.md

@@ -1,6 +1,10 @@
-# Code Gen
+# Enums Migration
 
-A helper program to generate some definations.
+A helper program to migrate existing Virtools enum declarations into other formats.
+
+Original Virtools SDK have various enum declarations. All of them are defined as C format and their formation are not uniform. This sub-project will use laxer and parser to recognize these diverse declarations, extract them as a series of uniform Java data struct and output them as C++ code (as C++ enum class syntax for LibCmo using), Python code (for PyBMap using), and C# code (for BMapSharp using).
+
+The steps processing existing enum declaration is called migration as this sub-project name told.
 
 ```
 antlr4 CKGeneralLexer.g4