feat(context): add idiomatic binding functions for clear err managment

[javierprovecho]

fix #662

[javierprovecho]

@appleboy I'm not sure what to do with BindJSON and others, they use BindWith which now uses MustBindWith...

[codecov-io]

Codecov Report

Merging #855 into develop will increase coverage by 0.03%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           develop     #855      +/-   ##
===========================================
+ Coverage    93.48%   93.51%   +0.03%     
===========================================
  Files           16       16              
  Lines         1351     1358       +7     
===========================================
+ Hits          1263     1270       +7     
  Misses          78       78              
  Partials        10       10

Impacted Files	Coverage Δ
context.go	89.41% <100%> (+0.03%)	⬆️
deprecated.go	66.66% <100%> (+66.66%)	⬆️

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[appleboy]

if we merge #636 PR, we can ignore this PR. right?

[javierprovecho]

@appleboy if 636 is merged, some behavior may be broken. this pr is the way to go, by using deprecated.go and a warning print for those who use bindwith

[sidbusy]

@javierprovecho Nice! Pls release new version ASAP, Thx!

[appleboy]

@sidbusy Yes. he is working on #871 v1.2 release.