Lab7: Expanded text.

Added ref to lab5

Author: janfrancu

docs/src/lecture_05/lab.md

@@ -1,4 +1,4 @@
-# Lab 05: Practical performance debugging tools
+# [Lab 05: Practical performance debugging tools](@id perf_lab)
 Performance is crucial in scientific computing. There is a big difference if your experiments run one minute or one hour. We have already developed quite a bit of code, both in and outside packages, on which we are going to present some of the tooling that Julia provides for finding performance bottlenecks. Performance of your code or more precisely the speed of execution is of course relative (preference, expectation, existing code) and it's hard to find the exact threshold when we should start to care about it. When starting out with Julia, we recommend not to get bogged down by the performance side of things straightaway, but just design the code in the way that feels natural to you. As opposed to other languages Julia offers you to write the things "like you are used to" (depending on your background), e.g. for cycles are as fast as in C; vectorization of mathematical operators works the same or even better than in MATLAB, NumPy. 
 
 

docs/src/lecture_07/hw.md

@@ -14,14 +14,13 @@ world = @ecosystem begin
     @add 3 Wolf             # adds 5 wolf with random sex
 end
 ```
+`@add` should not be treated as a macro, but rather just as a syntax, that can be easily matched.
+
 As this is not a small task let's break it into 3 steps
 1. Define method `default_config(::Type{T})` for each `T` in `Grass, Wolf,...`, which returns a tuple of default parameters for that particular agent.
 2. Define method `_add_agents(max_id, count::Int, species::Type{<:Species})` and `_add_agents(max_id, count::Int, species::Type{<:AnimalSpecies}, sex::Type{<:Sex})` that return an array of `count` agents of species `species` with `id` going from `max_id+1` to `max_id+count`. Default parameters should be constructed with `default_config`.
 3. Define the underlying function `_ecosystem(ex)`, which parses the block expression and creates a piece of code that constructs the world.
 
-!!! info "`Type{T}` type"
-    Some hints about this signature, which we have not yet introduced.   
-
 You can test the macro (more precisely the `_ecosystem` function) with the following expression
 ```julia
 ex = :(begin