WalrusFileManager: doc fix
WalrusFileManager: minor fix and improvment
WalrusFileManager: two new functions, filerPathJoin and pathJoin to construct path with DIRECTORY_SEPARATOR
Env: no more const, only $_ENV
WalrusKernel: check database conf before trying to connect
WalrusKernel: use of Walrus compile
WalrusRouter: use walrus compile
WalrusRouter: no more route.yml file
WalrusCompile: new core class