Add issue template

.github/issue_template.md

@@ -0,0 +1,30 @@
+:warning: This is a issue tracker, please use our mailing list for questions: www.pcl-users.org. :warning: 
+
+<!--- Provide a general summary of the issue in the Title above -->
+
+## Your Environment
+<!--- Include as many relevant details about the environment you experienced the bug in -->
+* Operating System and version:
+* Compiler:
+* PCL Version:
+
+## Expected Behavior
+<!--- If you're describing a bug, tell us what should happen -->
+<!--- If you're suggesting a change/improvement, tell us how it should work -->
+
+## Current Behavior
+<!--- If describing a bug, tell us what happens instead of the expected behavior -->
+<!--- If suggesting a change/improvement, explain the difference from current behavior -->
+
+## Possible Solution
+<!--- Not obligatory, but suggest a fix/reason for the bug, -->
+<!--- or ideas how to implement the addition or change -->
+
+## Code to Reproduce
+<!--- Provide a link to a live example, or an unambiguous set of steps to -->
+<!--- reproduce this bug. Include code to reproduce, if relevant -->
+
+## Context
+<!--- How has this issue affected you? What are you trying to accomplish? -->
+<!--- Providing context helps us come up with a solution that is most useful in the real world -->
+