add CapitalMode to StringConverter::Filter

[waybeforenow]

Fixes #137

Note that the documentation says

The first character will be uppercase, all others lowercase.

Here we look for the first (alphanumeric) character, pass it to std::toupper, then pass the remaining alphanumeric characters through std::tolower. Let me know if the desired behavior of the filter is different from this and I'll modify the PR accordingly.

[flexferrum]

Thanks for contributing!

Here we look for the first (alphanumeric) character, pass it to std::toupper, then pass the remaining alphanumeric characters through std::tolower.

I've checked the behavior of this filter in the python Jinja2 and looks like this implementation corresponds to the original capitalize filter behavior in general. So, everything is ok with it except of 'first alphanumeric'. ' user Name1' | capitalize gives user name1.

[codecov]

Codecov Report

Merging #139 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #139      +/-   ##
==========================================
+ Coverage   87.25%   87.26%   +0.01%     
==========================================
  Files          64       64              
  Lines        7209     7219      +10     
==========================================
+ Hits         6290     6300      +10     
  Misses        919      919

Impacted Files	Coverage Δ
src/string_converter_filter.cpp	92.85% <100%> (+0.44%)	⬆️
test/filters_test.cpp	100% <100%> (ø)	⬆️

---

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 2b26969...763fccd. Read the comment docs.

[waybeforenow]

I changed it so that capitalize only capitalizes the first character of the string regardless of whether it's alphanumeric.

(And if !isAlpha(ch), we don't need to invoke std::toupper or std::tolower at all.)

[flexferrum]

@waybeforenow , do you want to wait until October, 1st with this PR or I can merge it now?

[waybeforenow]

Thanks for asking ☺️ You can merge it whenever you like, I’m just happy to contribute.

…

On Thu, Sep 26, 2019 at 4:17 AM, Flex Ferrum ***@***.***> wrote: ***@***.***(https://github.com/waybeforenow) , do you want to wait until October, 1st with this PR or I can merge it now? — You are receiving this because you were mentioned. Reply to this email directly, [view it on GitHub](#139?email_source=notifications&email_token=AJC3RGHJ3TXPQRIHXAMK7LTQLSK3HA5CNFSM4I2P3P52YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD7VG6TI#issuecomment-535457613), or [mute the thread](https://github.com/notifications/unsubscribe-auth/AJC3RGGPS2VUD7XUO7B6HATQLSK3HANCNFSM4I2P3P5Q).

[flexferrum]

Thank you!