unix_time and convert_date (#332)

* very simple stuff

* added unix_date and imporved unix_time

* Update docs/scarpet/api/Auxiliary.md

Co-authored-by: gnembon <41132274+gnembon@users.noreply.github.com>

* Update Full.md

* Dont 100% work, but It'll do untl I fix tomorrow

* works, I think

* changeing weekdays

* removing weird stuff I didnt mean to do

* previous commits

* moving to expression.java

because prof.gnembon said

* moving away from LazyFUnctions

cos gnembon doesn't like evaluating somewhere

* updating docs

* tweaks to dates

Co-authored-by: Ghoulboy78 <ghoulboy27@gmail.com>

docs/scarpet/Full.md

@@ -921,6 +921,52 @@ flip_my_world_upside_down();
 print(str('this took %d milliseconds',time()-start_time))
 </pre>
 
+### `unix_time()`
+
+Returns standard POSIX time as a number of milliseconds since the start of the epoch 
+(00:00 am and 0 seconds, 1 Jan 1970).
+Unlike the previous function, this can be used to get exact time, but it varies from time zone to time zone.
+
+### `convert_date(milliseconds)`
+### `convert_date(year, month, date, hours?, mins?, secs?)`
+### `convert_date(l(year, month, date, hours?, mins?, secs?))`
+
+If called with a single argument, converts standard POSIX time to a list in the format: 
+
+`l(year, month, date, hours, mins, secs, day_of_week, day_of_year, week_of_year)`
+
+eg: `convert_date(1592401346960) -> [2020, 6, 17, 10, 42, 26, 3, 169, 25]`
+
+Where the `6` stands for June, but `17` stands for 17th, `10` stands for 10am,
+`42` stands for 42 minutes past the hour, and `26` stands for 26 seconds past the minute,
+and `3` stands for Wednesday, `169` is the day of year, and `25` is a week of year. 
+
+Run `convert_date(unix_time())` to get current time as list.
+
+
+When called with a list, or with 3 or 6 arguments, returns standard POSIX time as a number of milliseconds since the
+ start of the epoch (1 Jan 1970),
+using the time inputted into the function as opposed to the system time.
+
+Example editing:
+<pre>
+date = convert_date(unix_time());
+
+months = l('Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec');
+
+days = l('Mon','Tue','Wed','Thu','Fri','Sat','Sun');
+
+print(
+  str('Its %s, %d %s %d, %02d:%02d:%02d', 
+    days:(date:6-1), date:2, months:(date:1-1), date:0, date:3, date:4, date:5 
+  )
+)  
+</pre>
+
+This will give you a date:
+
+It is currently `hrs`:`mins` and `secs` seconds on the `date`th of `month`, `year`
+
 ### `profile_expr(expression)`
 
 Returns number of times given expression can be run in 50ms time. Useful to profile and optimize your code.