Various PRs from fork

[Jonfor]

As suggested by maxwey and merged into my fork you can get rid of unneeded memory allocations when using string builders instead of byte buffers. See the PR here: DataWiseHQ#11

I would also suggest this fix for a vulnerability in the form of an integer overflow on conversion: https://github.com/DataWiseHQ/grule-rule-engine/pull/4/files#diff-cbc54b7dd48a6702ecb844a59d4b1254b6ed0e09331797bc4f74c657c7c48b6eR39-R42

Here is a PR from recon2710 adding zerolog support: DataWiseHQ#7

I also made a PR that does a lot at once but I think replacing ioutil, which is deprecated, with os, is a good idea as well: DataWiseHQ#8

There are also a lot of references to old versions of go that can be updated like in the docs: https://github.com/hyperjumptech/grule-rule-engine/blob/master/docs/en/Tutorial_en.md referencing 1.16

I'm not sure how or if you want new PRs made for these? LMK!

[newm4n]

Also PRed about the version reverenced in Docs, it was merged in.

[newm4n]

Also added the int overflow protection. Thanks a lot.

[newm4n]

#Status: Open.
#491 @Jonfor @WilliamDeBruin @maxwey @recon2710