Split module to separated packages

[gucio321]

Hi everyone!
Here I present a whole-new layout of cimgui-go.
This was discussed in, and will fix #25

Now, instead of having everything in cimgui-go package, there are 4 smaller packages for each plugin.
In theory, it also reduces build time as it allows to parallelize implot, imnodes and immarkdown build.

results

on main:

real	2m32.649s
user	3m5.343s
sys	0m6.430s

on this PR

real	2m32.279s
user	3m6.522s
sys	0m6.435s

tested on ebiten example with time go build -a -v

@AllenDang this is a quite large change so I'll let you review and merge

[gucio321]

@AllenDang maybe we should tag current master and publish some release as this pr is done is done?
I'd suggest v1.0.0 as I don't expect any backward-incompatible changes in the future, however we might want to wait with v1 for #224. If so we can release v0.1.0 which doesn't have to keep up with any compatibility rules.

[AllenDang]

@AllenDang maybe we should tag current master and publish some release as this pr is done is done? I'd suggest v1.0.0 as I don't expect any backward-incompatible changes in the future, however we might want to wait with v1 for #224. If so we can release v0.1.0 which doesn't have to keep up with any compatibility rules.

Agree, let's release v1.0.0!

[gucio321]

@AllenDang Release notes are ready. You should be able to see them.
Could you please take a look and check if everything is correct? https://github.com/AllenDang/cimgui-go/releases/tag/untagged-dff92b68e1384b851b54

[AllenDang]

@gucio321 Great work! I've read, awesome, looks everything is ready, please release it! Congratulations!