Ensure socket is closed after processing in SSLServer

v0.7.18

Fixed problem with invalid requests including spaces in URL path

MultiparFormData parse problem on Client

v0.7.17

Removed `std::atomic<Error> error_`

Fix multiple threading bugs

v0.7.16

Fixed build errors and apply clangformat

Fixed stack smashing problem due to misuse of select

v0.7.15

std::tolower is undefined if the argument's value is neither represen…

Fixed error_handler problems

v0.7.14

Fix #738

Fix for SSL_connect problem and range problems

v0.7.13

Fix problem with invalid range

Fix digest auth proxy connection

v0.7.12

Fix #731

Fixed SSL read timeout problem

v0.7.11

Fixed compiler error for old compiler.

Temporary fix for memory leak on SSL

Please see #706 to find more information.

set_mount_point accepts HTTP headers

Add `cache_control` parameter to `set_mount_point` (#688)

* Add `cache_control` parameter to `set_mount_point`

Specifies the Cache-Control header value to return when specified. For example:

```
svr.set_mount_point("/assets", "public/assets", "public, max-age=604800, immutable");
```

* Add default for cache_control

Default to "no-cache", which is implicitly what is happening today.

* Change set_mount_point to accept Headers

* Don't use C++17 destructuring