I started working on a little ESP8266 project again. This time with an ESP-12 module from Ai-Thinker. Therefore I created a new part in Eagle after the specifications from Ai-Thinker (Technical Specifications).
My purchased module has a slightly different silkscreen as shown in the document. The module I have has GPIO4 and GPIO5 swapped and pin EN is labeled CH_PD. Make sure you check your module before using this library.