Edwh-pipcompile-plugin

Feature
* You can now compile/upgrade/... multiple items at the same time by comma-separating them ([`caae17c`](https://github.com/educationwarehouse/edwh-pipcompile-plugin/commit/caae17ce4017bcb7ca36ae312afee5d6b87b13c4))

Feature
* **compile:** Compile and upgrade can now also combine multiple .in files ([`2748f8c`](https://github.com/educationwarehouse/edwh-pipcompile-plugin/commit/2748f8cf06c0a5890a91827752c3871b12092a0e))
* Allow merging multiple .in files (for whitelabel etc) ([`de9b19d`](https://github.com/educationwarehouse/edwh-pipcompile-plugin/commit/de9b19d2368da47fbd36eeab01852e2d0ab5fd73))

Fix

* `pip-compile` executable sometimes not found ([`50677e7`](https://github.com/educationwarehouse/edwh-pipcompile-plugin/commit/50677e7da3e049cc823af43dd93652b0a1ec5048))

Feature
* Import main tasks to __init__ so this plugin can be used as a library ([`61611cf`](https://github.com/educationwarehouse/edwh-pipcompile-plugin/commit/61611cf0f795221615e4e802bf8209280b1ef854))

Fix
* **compile:** Reverting change ([`6651cd7`](https://github.com/educationwarehouse/edwh-pipcompile-plugin/commit/6651cd77a07dfe9a7befee5bea39bfeff61ae061))