Validate dataset

[snowboardit]

Related to #3. This is an on-going issue as new languages are added.

Go through every language in the dataset and make sure it is accurate and up to date.

Languages:

• java
• python
• javascript
• c-sharp
• c-plus-plus
• c
• typescript
• ruby
• swift
• kotlin
• go
• rust
• php
• dart
• objective-c
• scala
• perl
• lua
• haskell
• mysql
• postgres
• sql-server
• sql-lite