add index of faq

.gitignore

@@ -45,7 +45,6 @@ nbactions*.xml
 
 # Generated files
 /out/
-/doc/
 /gen/
 /gen3/
 /gen4/

doc/faq/index.md

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+# Frequently-Asked Questions
+
+## Getting Started
+
+* How to I install and run a simple grammar?
+* Why does my parser test program hang?
+
+## Installation
+
+* Why can't ANTLR (grun) find my lexer or parser?
+* Why can't I run the ANTLR tool?
+* Why doesn't my parser compile?
+
+## General
+
+* Why do we need ANTLR v4?
+* What is the difference between ANTLR 3 and 4?
+* Why is my expression parser slow?
+
+## Grammar syntax
+
+## Lexical analysis
+
+* How can I parse non-ASCII text and use characters in token rules?
+* How do I replace escape characters in string tokens?
+* Why are my keywords treated as identifiers?
+* Why are there no whitespace tokens in the token stream?
+
+## Parse Trees
+
+* How do I get the input text for a parse-tree subtree?
+* What if I need ASTs not parse trees for a compiler, for example?
+* When do I use listener/visitor vs XPath vs Tree pattern matching?
+
+## Translation
+
+* ASTs vs parse trees
+* Decoupling input walking from output generation
+
+## Actions and semantic predicates
+
+* How do I test if an optional rule was matched?
+
+## Error handling
+
+* How do I perform semantic checking with ANTLR?