Please add support for Seed7

## Language name
[Seed7](http://seed7.sourceforge.net)

## URL of example repository
Highlighted examples are [here](http://seed7.sourceforge.net/examples/index.htm) and in the sub pages of the [algorithms](http://seed7.sourceforge.net/algorith/index.htm).
Currently non-highlighted examples are at:
https://github.com/ThomasMertes/seed7/tree/master/prg
https://github.com/ThomasMertes/seed7/tree/master/lib

## URL of syntax highlighting grammar
Since Seed7 is also about syntax extensions this is not so easy to do. But the [Seed7 Homepage](http://seed7.sourceforge.net) uses syntax highlighting that can be used as guideline. You can see in the [Seed7 examples](http://seed7.sourceforge.net/examples/index.htm) which colors are used.

**Keywords** are blue (CSS: { color: blue} ). The keywords are: begin, case, const, do, downto, else, elsif, end, enum, for, forward, func, if, in, include, inout, is, local, new, of, otherwise, param, range, ref, repeat, return, struct, sub, syntax, system, then, to, until, val, var, when, while
**Operator symbols** are also blue. The operator symbols are: and, conv, digits, div, exp, in, lpad, lpad0, mdiv, mod, mult, not, or, parse, rem, rpad, sci, times, varConv
**Types** are red (CSS { color: red } ). Predefined type names are: array, func, hash, set, varfunc, bigInteger, bigRational, bitset, boolean, char, clib_file, color, complex, duration, expr, file, float, integer, object, proc, program, rational, reference, ref_list, string, text, time, type, void, PRIMITIVE_WINDOW
**Comments** are green (CSS: { color: green } ). There are line comments that start with a # and extend to the end of the line. There are also block comments that start with (* and end with *) . Block comments can nest.
**String and char literals** are maroon (CSS: { color: maroon } ). Strings literals start and end with " . A backslash can be used to escape a " inside a string literal. Char literals start and end with ' . A backslash can be used to escape a ' inside a char literal.

## Most popular extensions
.sd7
.s7i

## Detected language

.sd7 Seed7 program
.s7i Seed7 library