GitHub community issue/contribution changes (#75)

Overhauled Mapbase's GitHub-specific files to be more effective and project-agnostic

* Moved CONTRIBUTING to .github so it can be recognized as contribution guidelines
* Added more issue templates and made them more project-agnostic for forks
* Renamed issue templates so "Bug report", "Feature request", etc. come first when looking for the right template
* Added pull request template

.github/ISSUE_TEMPLATE/bug-report---code.md

@@ -0,0 +1,25 @@
+---
+name: Bug report - Code
+about: Create a bug report related to the source code itself. (e.g. a compile error)
+title: "[CODE] "
+labels: Bug
+assignees: ''
+
+---
+
+### Describe the bug
+A clear and concise description of what the bug is.
+
+### Steps to reproduce
+Steps to reproduce the behavior:
+1. Have '...' set to something
+2. ???
+3. See error
+
+### Expected behavior
+A clear and concise description of what you expected to happen.
+
+---
+
+### Additional context
+(Optional) Add any other context about the problem here.