style: enhance and reformat issue template

Add missing required information for new issues
Redo Markdown format for a cleaner raw display
Standarise requirements/terms with CONTRIBUTING.md

CONTRIBUTING.md

@@ -4,15 +4,14 @@
 * If you aren't sure, you can ask on the [**IRC channel**](https://webchat.freenode.net/?channels=qtox) or read our [**wiki**](https://github.com/tux3/qTox/wiki) first.
 * Do a quick **search**. Others might have already reported the issue.
 * Write in **English**!
-* Provide **version** information: (You can find version numbers in menu `Settings → About`)
-  ```
-qTox: 
+* Provide **version** information (you can find version numbers in menu `Settings → About`):
+```
+OS: 
+qTox version: 
 Commit hash: 
 toxcore: 
 Qt: 
-OS version: 
-
-  ```
+```
 * Provide **steps** to reproduce the problem, it will be easier to pinpoint the fault.
 * **Screenshots**! A screenshot is worth a thousand words. Just upload it. [(How?)](https://help.github.com/articles/file-attachments-on-issues-and-pull-requests)
 
@@ -25,7 +24,7 @@ OS version:
 # Opening a pull request
 
 ### Must read
-* Use **[commit message format](#commit-message-format)**.
+* Use [**commit message format**](#commit-message-format).
 * Read our [**coding guidelines**](https://github.com/tux3/qTox/wiki/Coding).
 * Keep the title **short** and provide a **clear** description about what your pull request does.
 * Provide **screenshots** for UI related changes.

ISSUE_TEMPLATE.md

@@ -1,29 +1,32 @@
-Brief description:
-
-Operating System: Windows / OS X / Linux (include version and/or distro)  
-qTox version: (shown on `About` page in settings)  
-Hardware: 
+#### Brief Description
+
+OS: Windows / OS X / Linux (include version and/or distro)  
+qTox version: (version numbers in menu `Settings → About`)  
+Commit hash:  
+toxcore:  
+Qt:  
+Hardware:  
 …
 
 Reproducible: Always / Almost Always / Sometimes / Rarely / Couldn't Reproduce
 
+#### Steps to reproduce
 
-**Steps to reproduce:**  
-1.  
-2.  
-3.  
-…
-
+1. 
+2. 
+3. …
 
-**Observed Behavior:**  
+#### Observed Behavior
 
 
-**Expected Behavior:**  
+#### Expected Behavior
 
 
-**Additional info:**  
+#### Additional Info
 (links, images, etc go here)
 
 ----
 
-More information on how to write good bug reports in the wiki: https://github.com/tux3/qTox/wiki/Writing-Useful-Bug-Reports
+More information on how to write good bug reports in the wiki: https://github.com/tux3/qTox/wiki/Writing-Useful-Bug-Reports.
+
+Please remove any unnecessary template section before submitting.