feat(refacto): move everything in internal package

This allows to install katenary with `go install` and to clean up the
project folder.

doc/docs/packages/internal/parser.md

@@ -0,0 +1,19 @@
+<!-- Code generated by gomarkdoc. DO NOT EDIT -->
+
+# parser
+
+```go
+import "github.com/katenary/katenary/internal/parser"
+```
+
+Package parser is a wrapper around compose\-go to parse compose files.
+
+## func [Parse](<https://github.com/katenary/katenary/blob/master/internal/parser/main.go#L29>)
+
+```go
+func Parse(profiles []string, envFiles []string, dockerComposeFile ...string) (*types.Project, error)
+```
+
+Parse compose files and return a project. The project is parsed with dotenv, osenv and profiles.
+
+Generated by [gomarkdoc](<https://github.com/princjef/gomarkdoc>)