build: added more options to optimize release binary size

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I am still a bit of a newb to Rust myself so I am not fully confident in the best opt-level to use, or to leave it as default (0). For doge, I'd be tempted to desire smaller binaries at the cost of performance; I'm not sure that its use case is one where you're going to see a noticeable change anyway...I tried to do some benchmarks with hyperfine and every command I ran (even with the opt-level "z" binary) ran in under 2.5ms.

Meanwhile, the reduction in binary in size, depending on the target, can be pretty significant.

Here are the numbers based on the v0.2.9 release and this run on my fork:

Target	Before	After	Reduction
linux-x86_64	6.8M	6.6M	3%
linux-i686	5.1M	4.9M	4%
linux-aarch64	6.0M	5.2M	13%
linux-armv7	3.9M	3.1M	21%
apple	2.4M	1.9M	21%
windows-x86_64	1017K	864K	15%
windows-i686	779K	640K	18%

opt-level 3

Out of my own curiosity, I wanted to see the difference between opt-level = "z" and opt-level = 3. Here's the comparison for this run on my fork:

Target	Before	After	Reduction
linux-x86_64	6.8M	6.7M	1%
linux-i686	5.1M	5.0	2%
linux-aarch64	6.0M	5.3M	12%
linux-armv7	3.9M	3.2M	18%
apple	2.4M	2.2M	8%
windows-x86_64	1017K	978K	4%
windows-i686	779K	752K	3%

So opt-level = "z" seems to be have way more of an affect on apple and windows and less on linux, which I find fascinating.

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Unrelated typos I noticed but not really worth their own PR IMO