Add input type hinting, remove duplicate code, improve Docblock, add some optimizations

[ker0x]

This PR do:

• add input type hinting for methods (as the minimum PHP version is set to 7.0 in composer.json)
• remove some duplicate code already present in parent or abstract class
• improve Docblock
• add small optimizations

Warning

If this PR is merged, the next release should be tag 2.0 as it bring I/O type hinting. By doing so, this will avoid BC break for people using version < 2.0

[codecov[bot]]

Codecov Report

Merging #87 into master will decrease coverage by 0.61%. The diff coverage is 78.36%.

@@             Coverage Diff             @@
##             master     #87      +/-   ##
===========================================
- Coverage     71.32%   70.7%   -0.62%     
+ Complexity      477     429      -48     
===========================================
  Files            49      49              
  Lines          1332    1304      -28     
===========================================
- Hits            950     922      -28     
  Misses          382     382

Impacted Files	Coverage Δ	Complexity Δ
src/Extensions/ListTemplate.php	71.42% <ø> (ø)	10 <0> (ø)	:arrow_down:
src/Extensions/Airline/AirlineFlightInfo.php	100% <ø> (ø)	1 <0> (ø)	:arrow_down:
src/Commands/Nlp.php	0% <0%> (ø)	4 <0> (ø)	:arrow_down:
src/Commands/AddGreetingText.php	0% <0%> (ø)	4 <0> (ø)	:arrow_down:
src/Commands/AddPersistentMenu.php	0% <0%> (ø)	4 <0> (ø)	:arrow_down:
src/Extensions/AirlineUpdateTemplate.php	27.58% <0%> (ø)	5 <3> (ø)	:arrow_down:
src/Commands/WhitelistDomains.php	0% <0%> (ø)	4 <0> (ø)	:arrow_down:
src/Extensions/AirlineCheckInTemplate.php	28% <0%> (ø)	4 <2> (ø)	:arrow_down:
src/Commands/AddStartButtonPayload.php	0% <0%> (ø)	4 <0> (ø)	:arrow_down:
src/Extensions/ReceiptAddress.php	93.1% <100%> (ø)	9 <6> (ø)	:arrow_down:
... and 31 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 5ccdd07...ec27b6d. Read the comment docs.

[feralheart]

Hi @ker0x, Thank you for your contribution. Sorry, but I can't accept it at the moment, because it adds more new features in one PR. Can you send separate PR/feature? For more information about contributing check our contribution guide