parser: add basic statements

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
lexer: add method to read token without spaces

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
parser: add parsing api

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
parser: add valuable state to statements

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
tests: enable parser test

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
parser: add boolean statement

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
parser: basic let statement work

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>