typos & todos
fix label typo and mention that multiple -D flags are allowed (closes #53)
document iterators
document resource embedding (closes #44)
Merge pull request #54 from nadako/development

document resource embedding (closes #44)
document externs
document haxelib (part 1)
parser fixes & todo
deal with a bunch of \todo
Merge branch 'development' of https://github.com/Simn/HaxeManual into development
added \todo and a workflow for constructing flowcharts
tikz.tex contains all the flowchart / tikz related packages and definitions, requires tikz, tkz-euclide, shapes.geometric, arrows and tikz-qtree (pretty sure all of them should be in texlive at least)
replaced class field var initialization \includegraphics with a tikz qtree drawn flowchart
changed -x convert to -neko convert.n and added neko convert.n to build commands (more robust this way, -x can make errors in neko crash/break/stall haxe)
added support for custom environments to LatexLexer, allows for entire environments to be captured and returned as a string in a TCustomEnvironment
added support for pdflatex compilation of flowcharts to markdown conversion, creates pngs from flowchart environments and embeds them into markdown as image links
above compilation requires an existing assets/graphics/generated/ dir, pdflatex and convert (from imagemagick) in PATH and either "-D compileEnv" (doesn't compile existing images) or "-D recompileEnv" (deletes existing images and tries recompiling all of them)
-D keepEnvTemp is also availabile, which keeps the temporary latex compilation dir and tex (and overwrites them if they exist already, instead of complaining)
envTemplate.tex in convert/ is a template that's used for the pdflatex compilation step to allow for successful snippet compilation (this can be optimized by precompiling, but that's for later), added as -resource and used in the parser