Add package dependencies to travis script.
waf: Add descriptions to custom waf build targets.
Add Travis CI status image/link
Update README.md, fix dependency list, refer ./waf instead of waf.
Add draft HACKING.md
doc: minor fixes to ARCHITECTURE
waf: bump version to 0.83.2 (overdue)
test: add type init compat code for glib < 2.36.0
Sheet: Use `grid_item` instead of `grid`, fixes #96.

Also add some minor amounts of documentation.
test: Use preprocessor for glib version check conditional.
Transform coords "pos" to cairo_matrix_t "transform"

This is the first step for implementing the whole rotate/move properly (2nd attempt),
all based on cairo_matrix_t which can  and will be reused for proper drawing too.
Every transform regarding 0,0 on the sheet shall be described with that matrix.
To undo something the simply a stack of matrices of each item can be kept and reverted to at
will.
Always use TRUE/FALSE macros as return values instead of 0/-1.
NodeStore: Use NG_DEBUG for warnings in wire placement.
ItemData: Properly include GooCanvas header.
Node: Use gboolean instead of gint, refine hash func for different int widths.
Part: Recenter part boundingbox on rotation, add documentation.
Sheet: Reduce complexity of event handling.
PartItem: Use CairoMatrix to transform view representation.
ItemData, PartItem, Part: Use g_slice_* for private instance data.
Schematic: Init grid field of ItemData items when loaded from file.