add a new module system

# -----------------------------------------------------------------------------

add_custom_target(doc

    COMMAND mkdir -p ${CMAKE_CURRENT_BINARY_DIR}/wwwdocs

    COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/doc/web/build.sh ${CMAKE_CURRENT_BINARY_DIR}/wwwdocs)

    COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/doc/web/build.sh ${clip_VERSION} ${CMAKE_CURRENT_BINARY_DIR}/wwwdocs)

file(GLOB doc_figure_files "doc/**/*.clp")

foreach(doc_figure_path ${doc_figure_files})

<div align="center"><img src="./doc/logo.svg" alt="clip" width="160" /></div>

<h3>clip – The command line illustration processor</h3>

clip

====

clip (the _command line illustration processor_) is an open-source command line

program and software library for creating charts and other programmatic

illustrations. In essence, clip consists of a library of drawing commands. This

command library includes high-level building blocks for creating common chart

types as well as lower-level drawing primitives such as markers, arrows and lines.

program and software library for creating charts and other data-driven

illustrations.

<h4>

  <a href="https://clip-lang.org/getting-started">Getting Started</a> &middot;

Introduction

------------

Being a highly visual tool, clip is best explained by example. So here is how to

draw a simple line chart using clip):

In essence, clip is an automated drawing program; it reads a text file containing

a description of the chart or diagram and produces an image from it. This is best

explained by example, so here is how to draw a simple line chart using clip:

    $ clip --export example_chart.svg example_chart.clp

    (class plot)

The command reads an input file (`example_chart.clp`) and produces an output SVG

file from it. This is the input file:

    (axes

        label-format-x (datetime "%H:%M:%S"))

    (figure/plot

        limit-x (0 7200)

        limit-y (0 100)

        lines (

    (grid

        stroke-color #333

        stroke-style dashed)

    (lines

        data-x (csv "measurement.csv" time)

        data-y (csv "measurement.csv" value)

        stroke-width 0.8pt)

        grid (

            stroke-color #333

            stroke-style dashed))

The resulting SVG file looks like this:

The input file from above (`example.clp`) can be processed with clip using the

following command:

    $ clip --export output.svg example.clp

This is the resulting SVG file (`output.svg`):

<div align="center">

  <a href="https://clip-lang.org/examples/charts-scientific/vectorfield">

  <a href="https://clip-lang.org/examples/charts-scientific/multiple_y_axes">

    <img src="/doc/demo.svg" width="80%" alt="Demo Chart" />

  </a>

</div>

Installation

------------

#### Using homebrew (macOS)

To install clip using homebrew, run the following command:

    $ brew install clip

#### Compile from source

To build clip, you need an up-to-date C++ compiler, cmake, fmtlib, libharfbuzz,

The `<color>` setting allows you to configure colors. The following ways to

specify colors are supported:

    ;; specify a color by hex code or reference a color from the color palette

    <color-code>

    ;; specify a color by hex code

    #rgb

    #rrggbb

    #rrggbbaa

    ;; specify a color by rgb. components should be in the range 0..1

    (rgb <r> <g> <b>)

(layer/resize 2048px 768px)

(layer/set-dpi 240)

(layer/set-font "Latin Modern Roman")

(size 2048px 768px)

(dpi 240)

(font "Latin Modern Roman")

(limit-x (0 7200))

(limit-y (0 100))

(figure/plot

    limit-x (0 7200)

    limit-y (0 100)

    axes (

(axes

    label-format-x (datetime "%H:%M:%S")

    label-placement-x (linear-interval 900 900 7000))

    grid (

(grid

    stroke-color (rgba 0 0 0 0.2)

    stroke-style dashed

    tick-placement-x (none))

    lines (

(lines

    data-x (csv "test/testdata/timeseries.csv" time)

    data-y (csv "test/testdata/timeseries.csv" value)

        stroke-width 0.8pt))

    stroke-width 0.8pt)

(figure/plot

    lines (

(lines

    data-x (100 200 300 400 500 600 700 800 900)

    data-y (1.2 1.8 1.3 1.6 1.5 1.3 1.8 1.9 2.0)

    limit-y (0 3)

    limit-x (0 1000)

    marker-shape (pentagon)

        marker-size 8pt))

    marker-size 8pt)